cs-tagset 20260531

Tags and sets of tags with __format__ support and optional ontology information.

Tags and sets of tags with format support and optional ontology information.

Latest release 20260531:

• New TagSetTyping mixin for TagSets providing .type_name, .type_key, .type_zone and .type_subname properties based on partitioning .name into zone.type_subname.key; inherited by TagSet.
• New HasTags mixin for classes whose instances have a .tags attribute which is a TagSet, proxying several mapping methods .deref, and getattr to the .tags.
• BaseTagSets: new deref(TagSet) method to dereference values in a TagSet's tags to their corresponding TagSets.
• New UsesTagSets, the bulk of UsesSQLTags, deref which promotes the result of BaseTagSets.deref and relies on subclasses to provide a .find(), such as SQLTags.find.
• TagSet: drop get_value() and get_format_attribute().
• New TagSet.json() and HasTags.json() methods, usable as format conversions.
• New HasTags.printt() method calling cs.lex.printt().
• TagSet: new printt() method.
• jsonable: support transcribe datetime.date.
• tagset,fstags,sqltags: make _id only special to SQLTagSet (the db row id), drop all mentions elsewhere.
• TagSet.dump: make as obsolete, prefer TagSet.printt.
• TagSet and HasTags:: make Refreshable, drop the .is_stale() method, superceded by .refresh_needed().
• TagFile.save_tagset: have atomic_filename fall back to overwrite on PermissionError, uses new write_tagsets class method.
• HasTags: new .print() method for a nice summary, default calls .printt().
• Many other small changes.

See cs.fstags for support for applying these to filesystem objects such as directories and files.

See cs.sqltags for support for databases of entities with tags, not directly associated with filesystem objects. This is suited to both log entries (entities with no "name") and large collections of named entities; both accept Tags and can be searched on that basis.

All of the available complexity is optional: you can use Tags without bothering with TagSets or TagsOntologys or the persistence of domain knowledge classes.

This module contains the following primary classes:

• Tag: an object with a .name and optional .value (default None) and also an optional reference .ontology for associating semantics with tag values. The .value, if not None, will often be a string or a number, but may be any Python object. If you're using these via cs.fstags, the object will need to be JSON transcribeable.
• TagSet: a dict subclass representing a set of Tags to associate with something; it also has setlike .add and .discard methods. As such it only supports a single Tag for a given tag name, but that tag value can of course be a sequence or mapping for more elaborate tag values.
• BaseTagSets: a base class for collections of TagSets, subclassed to provide persistence, for example in a database a done with the cs.sqltags.SQLTags class

There is also support for persisting TagSets and using them for storing per-domain knowledge, see below.

Here's a simple example with some Tags and a TagSet.

>>> tags = TagSet()
>>> # add a "bare" Tag named 'blue' with no value
>>> tags.add('blue')
>>> # add a "topic=tagging" Tag
>>> tags.set('topic', 'tagging')
>>> # make a "subtopic" Tag and add it
>>> subtopic = Tag('subtopic', 'ontologies')
>>> tags.add(subtopic)
>>> # Tags have nice repr() and str()
>>> subtopic
Tag(name='subtopic',value='ontologies')
>>> print(subtopic)
subtopic=ontologies
>>> # a TagSet also has a nice repr() and str()
>>> tags
TagSet:{'blue': None, 'topic': 'tagging', 'subtopic': 'ontologies'}
>>> print(tags)
blue subtopic=ontologies topic=tagging
>>> tags2 = TagSet({'a': 1}, b=3, c=[1,2,3], d='dee')
>>> tags2
TagSet:{'a': 1, 'b': 3, 'c': [1, 2, 3], 'd': 'dee'}
>>> print(tags2)
a=1 b=3 c=[1,2,3] d=dee
>>> # since you can print a TagSet to a file as a line of text
>>> # you can get it back from a line of text
>>> TagSet.from_str('a=1 b=3 c=[1,2,3] d=dee')
TagSet:{'a': 1, 'b': 3, 'c': [1, 2, 3], 'd': 'dee'}
>>> # because TagSets are dicts you can format strings with them
>>> print('topic:{topic} subtopic:{subtopic}'.format_map(tags))
topic:tagging subtopic:ontologies
>>> # TagSets have convenient membership tests
>>> # test for blueness
>>> 'blue' in tags
True
>>> # test for redness
>>> 'red' in tags
False
>>> # test for any "subtopic" tag
>>> 'subtopic' in tags
True
>>> # test for subtopic=ontologies
>>> print(subtopic)
subtopic=ontologies
>>> subtopic in tags
True
>>> # test for subtopic=libraries
>>> subtopic2 = Tag('subtopic', 'libraries')
>>> subtopic2 in tags
False

Persistence

It is often desirable for TagSets to persist after your programme has ceased running. This is usually done by subclassing TagSet and BaseTagSets to load state from some storage and to mirror changes back to that storage. The usual subclasses for doing this with an SQL database are the SQLTagSet and SQLTags classes from cs.sqltags. Another example is the TaggedPath and FSTags classes from cs.fstags, where TaggedPath subclasses TagSet; these are used to store metadata about files in a filesystem.

Domain Knowledge

I've experimented with further subclassing, for example, SQLTagSet and SQLTags to represent domain knowledge, for example to cache MusicBrainzNG knowledge when ripping CDs. The direct subclassing approach scales poorly.

Instead the preferred approach is to use the HasTags and UsesTagSets base classes. The HasTags class is essentially a proxy which stores the entityt state in its .tags attribute, a TagSet and has a reference to a .tags_db, which is an instance of a UsesTagSets, the larger collection of TagSets. The UsesTagSets class has a .tagsets attribute referring to an instance of a BaseTagSets, a collection of TagSets.

It's important to know that BaseTagSets, HasTags, and UsesTagSets all have a .deref() method for dereferencing tags which refer to other entity ids.

Setting up a class for a particular knowledge domain requires defining 2 classes: a HasTags subclass to be the base class for members of the domain and a UsesTagSets class for the domain itself. Here is the basis of the MusicBrainzNG domain from cs.cdrip:

class _MBEntity(HasTags):
    ... common methods for all MB entities ...

class MBDB(UsesTagSets, MultiOpenMixin, RunStateMixin):
  """ An interface to MusicBrainz with a local `SQLTags` cache.
  """

  TYPE_ZONE = 'mbdb'
  HasTagsClass = _MBEntity
  TagSetsClass = MBSQLTags

The MBDB class subclasses UsesTagSets and defines the following class attributes:

• TYPE_ZONE: a name prefix for enetities in this domain, as typical use stores multiple domains in a common SQLTags database
• HasTagsClass: the base class for entities in this domain
• TagSetsClass: the BaseTagSets subclass which stores the entities; this will often be SQLTags; in this case the MBSQLTags class is just an SQLTags subclass with a different default location for the database

The purpose of the distinct HasTagsClass subclass for entities is so that UsesTags.__new__ can locate a further subclass for a particular entity based on its type; it starts its search at the HasTagsClass class. For example, _MBEntity has several subclasses for discs, releases and so forth. The MBDisc subclass starts like this:

class MBDisc(_MBEntity):
  """ A Musicbrainz disc entry.
  """

  TYPE_SUBNAME = 'disc'

In the shared SQLTags each disc has a .name of the form: mbdb.disc.discid The leading mbdb. identifies it as belonging to to the MBDB class matching its TYPE_ZONE attribute, and the following disc identifies the MBDisc class, matching its TYPE_SUBNAME attribute.

Accessing or creating an entity is done by indexing the MBDB instance:

disc = mbdb['disc', discid]

which will return an MBDisc instance, creating it in the database if necessary. To Avoid wiring in the type subname string you can also use the subclass:

disc = mbdb[MBDisc, discid]

Ontologies

Tags and TagSets suffice to apply simple annotations to things. However, an ontology brings meaning to those annotations.

There is also a TagsOntology, a mapping of type names to TagSets defining the type and also to entries for the metadata for specific per-type values. See the TagsOntology class for implementation details, access methods and more examples.

Consider a record about a movie, with these tags (a TagSet):

title="Avengers Assemble"
series="Avengers (Marvel)"
cast={"Scarlett Johansson":"Black Widow (Marvel)"}

where we have the movie title, a name for the series in which it resides, and a cast as an association of actors with roles.

An ontology lets us associate implied types and metadata with these values.

Here's an example ontology supporting the above TagSet:

type.cast type=dict key_type=person member_type=character description="members of a production"
type.character description="an identified member of a story"
type.series type=str
character.marvel.black_widow type=character names=["Natasha Romanov"]
person.scarlett_johansson fullname="Scarlett Johansson" bio="Known for Black Widow in the Marvel stories."

The type information for a cast is defined by the ontology entry named type.cast, which tells us that a cast Tag is a dict, whose keys are of type person and whose values are of type character. (The default type is str.)

To find out the underlying type for a character we look that up in the ontology in turn; because it does not have a specified type Tag, it it taken to be a str.

Having the types for a cast, it is now possible to look up the metadata for the described cast members.

The key "Scarlett Johansson" is a person (from the type definition of cast). The ontology entry for her is named person.scarlett_johansson which is computed as:

• person: the type name
• scarlett_johansson: obtained by downcasing "Scarlett Johansson" and replacing whitespace with an underscore. The full conversion process is defined by the TagsOntology.value_to_tag_name function.

The key "Black Widow (Marvel)" is a character (again, from the type definition of cast). The ontology entry for her is named character.marvel.black_widow which is computed as:

• character: the type name
• marvel.black_widow: obtained by downcasing "Black Widow (Marvel)", replacing whitespace with an underscore, and moving a bracketed suffix to the front as an unbracketed prefix. The full conversion process is defined by the TagsOntology.value_to_tag_name function.

Format Strings

You can just use str.format_map as shown above for the direct values in a TagSet, since it subclasses dict.

However, TagSets also subclass cs.lex.FormatableMixin and therefore have a richer format_as method which has an extended syntax for the format component. Command line tools like fstags use this for output format specifications.

An example:

>>> # an ontology specifying the type for a colour
>>> # and some information about the colour "blue"
>>> ont = TagsOntology(
...   {
...       'type.colour':
...       TagSet(description="a colour, a hue", type="str"),
...       'colour.blue':
...       TagSet(
...           url='https://en.wikipedia.org/wiki/Blue',
...           wavelengths='450nm-495nm'
...       ),
...   }
... )
>>> # tag set with a "blue" tag, using the ontology above
>>> tags = TagSet(colour='blue', labels=['a', 'b', 'c'], size=9, _ontology=ont)
>>> tags.format_as('The colour is {colour}.')
'The colour is blue.'
>>> # format a string about the tags showing some metadata about the colour
>>> tags.format_as('Information about the colour may be found here: {colour:metadata.url}')
'Information about the colour may be found here: https://en.wikipedia.org/wiki/Blue'

Short summary:

• as_unixtime: Convert a tag value to a UNIX timestamp.
• BaseTagSets: The base class for collections of TagSet instances such as cs.fstags.FSTags and cs.sqltags.SQLTags.
• HasTags: A mixin for classes which have a .tags:TagSet attribute.
• jsonable: Convert obj to a JSON encodable form. This returns obj for purely JSONable objects and a JSONable deep copy of obj if it or some subcomponent required conversion. converted is a dict mapping object ids to their converted forms to prevent loops.
• MappingTagSets: A BaseTagSets subclass using an arbitrary mapping.
• RegexpTagRule: A regular expression based Tag rule.
• selftest: Run some ad hoc self tests.
• Tag: A name/value pair. Each Tag has a .name (str), a .value and an optional .ontology. The name must be a dotted identifier.
• tag_or_tag_value: A decorator for functions or methods which may be called as:.
• TagBasedTest: A test based on a Tag.
• TagFile: A reference to a specific file containing tags.
• TagsCommandMixin: Utility methods for cs.cmdutils.BaseCommand classes working with tags.
• TagSet: A setlike class collection of Tags.
• TagSetCriterion: A testable criterion for a TagSet.
• TagSetPrefixView: A view of a TagSet via a prefix.
• TagSetsSubdomain: A view into a BaseTagSets for keys commencing with a prefix being the subdomain plus a dot ('.').
• TagSetTyping: A mixin to support TagSet types based on their .name attribute. These see proper use in the cs.sqltags.SQLTagSets class where dereferences of tag values to other TagSets may be done. This is used by the TagSet class and its subclasses.
• TagsOntology: An ontology for tag names. This is based around a mapping of names to ontological information expressed as a TagSet.
• TagsOntologyCommand: A command line for working with ontology types.
• UsesTagSets: A mixin to support classes which use a BaseTagSets to store their data.

Module contents:

• as_unixtime(tag_value): Convert a tag value to a UNIX timestamp.

  This accepts int, float (already a timestamp) and date or datetime (use datetime.timestamp() for a nonnaive datetime, otherwise time.mktime(tag_value.time_tuple())`, which assumes the local time zone).

• class BaseTagSets(cs.resources.MultiOpenMixin, collections.abc.MutableMapping): The base class for collections of TagSet instances such as cs.fstags.FSTags and cs.sqltags.SQLTags.

  Examples of this include:

  • cs.cdrip.MBSQLTags: a mapping of MusicbrainsNG entities to their associated TagSet
  • cs.fstags.FSTags: a mapping of filesystem paths to their associated TagSet
  • cs.sqltags.SQLTags: a mapping of names to TagSets stored in an SQL database

  Subclasses must implement:

  • get(name,default=None): return the TagSet associated with name, or default.
  • __setitem__(name,tagset): associate a TagSet with the key name; this is called by the __missing__ method with a newly created TagSet.
  • keys(self): return an iterable of names

  Subclasses may reasonably want to override the following:

  • startup_shutdown(self): a context manager to allocate and release any needed resources such as database connections; this is used via the MultiOpenMixin when the instance is used as a context manager

  Subclasses may implement:

  • __len__(self): return the number of names

  The TagSet factory used to fetch or create a TagSet is named TagSetClass. The default implementation honours two class attributes:

  • TAGSETCLASS_DEFAULT: initially TagSet
  • TAGSETCLASS_PREFIX_MAPPING: a mapping of type names to TagSet subclasses

  The type name of a TagSet name is the first dotted component. For example, artist.nick_cave has the type name artist. A subclass of BaseTagSets could utiliise an ArtistTagSet subclass of TagSet and provide:

  TAGSETCLASS_PREFIX_MAPPING = {
    'artist': ArtistTagSet,
  }
  

  in its class definition. Accesses to artist.* entities would result in ArtistTagSet instances and access to other entities would result in ordinary TagSet instances.

BaseTagSets.__init__(self, *, ontology=None): Initialise the collection.

BaseTagSets.TAGSETCLASS_DEFAULT

BaseTagSets.TagSetClass(self, *, name, **kw): Factory to create a new TagSet from name.

BaseTagSets.__contains__(self, name: str): Test whether name is present in the underlying mapping.

BaseTagSets.__getitem__(self, name: str): Obtain the TagSet associated with name.

If name is not presently mapped, return self.__missing__(name).

BaseTagSets.__iter__(self): Iteration returns the keys.

BaseTagSets.__len__(self): Return the length of the underlying mapping.

BaseTagSets.__missing__(self, name: str, **tags_kw) -> cs.tagset.TagSet: Like dict, the __missing__ method may autocreate a new TagSet.

This is called from __getitem__ if name is missing and uses the factory cls.default_factory, which may be None to disable autocreation; the default uses self.TagSetClass to create a new TagSet.

If the factory None raise KeyError. Otherwise call self.default_factory(name,**tags_kw). If that returns None raise KeyError. Otherwise save the entity under name and return the entity.

BaseTagSets.__setitem__(self, name, te): Save te in the backend under the key name.

BaseTagSets.add(self, name: str, **kw): Return a new TagSet associated with name, which should not already be in use.

BaseTagSets.default_factory(self, name: str, **tags_kw) -> cs.tagset.TagSet: Create a new TagSet named name.

BaseTagSets.deref(self, te: cs.tagset.TagSet, tag_name, attr=None, *, type_zone, subtype=None) -> Union[NoneType, cs.tagset.TagSet, List[cs.tagset.TagSet], List[Tuple[Any, cs.tagset.TagSet]]]: Dereference the tag tag_name through te, a TagSet. Return the entities it implies, using the tag value as the target entity key or keys.

The optional subtype parameter may be used to specify a target entity subtype instead of inferring it from tag_name as outlined below.

The return is variously:

• None if the tag_name is not present If attr is None then the tag value is a type key or list of type keys:
• a TagSet derived from the tag value
• a list of TagSets from a list of the tag values which are type keys If attr is not None then the tag value is an another tag value or list of tag values:
• a list of TagSet where the TagSet.attr matches the tag value
• a list of (value,List[TagSet]) from a list of tag values where the TagSet.attr matches each value These are detailed below.

Return None if the tag is not present. Otherwise the return depends on whether attr is not None and whether the tag value is a Sequence.

If attr is None, the lookup is done on the entity .name, which is {te.type_zone}.{subtype}.{key}. If the value is a Sequence then the default subtype is the tag_name, with a trailing _id removed if present, and the key is each element of the value in turn. If the value is not a Sequence then the subtype defaults to the tag_name and the key is the tag value.

If the attr is not None, the lookup is done on the entity tag named attr for entities whose .name starts with {te.type_zone}.{subtype}..

If the value is a Sequence then the default subtype is the tag_name with a trailing s removed if present and the key is each element of the value in turn, checked against each entity's tag; this returns a dict mapping each key to a list of the matching entities.

If the value is not a Sequence then the default subtype is the tag_name and the key is the tag value; this returns a list of the matching entities.

Some examples should clarify. Suppose we have te as the entity named tvdb.series.1234 with the following tag values:

characters  [56, 123, 78]
genres      ["Documentary", "Food"]
studio      99
episode     "Fred explores the foods of somewhere."

Then:

Calling deref(te,'characters') would return a list containing the entities named tvdb.character.56, tvdb.character.123, tvdb.character.78.

Calling deref(te,'genres', 'genre_title') would return a list of: [("Documentary",List[TagSet]),("Food",List[TagSet])] associating "Documentary" and "Food" to a list of entities whose .genre_title matched each genre and whose .name started with tvdb.genre..

Calling deref(te,'studio') would return the entity named tvdb.studio.99.

Calling deref(te,'episode', 'summary') would return a list of the entities whose .summary was "Fred explores the foods of somewhere." and whose .name starts with tvdb.episode..

BaseTagSets.edit(self, *, select_tagset=None, **kw): Edit the TagSets.

Parameters:

• select_tagset: optional callable accepting a TagSet which tests whether it should be included in the TagSets to be edited Other keyword arguments are passed to Tag.edit_tagsets.

BaseTagSets.get(self, name: str, default=None): Return the TagSet associated with name, or default if there is no such entity.

BaseTagSets.items(self, *, prefix=None): Generator yielding (key,value) pairs, optionally constrained to keys starting with prefix+'.'.

BaseTagSets.keys(self, *, prefix=None): Return the keys starting with prefix+'.' or all keys if prefix is None.

BaseTagSets.subdomain(self, subname: str): Return a proxy for this BaseTagSets for the names starting with subname+'.'.

BaseTagSets.values(self, *, prefix=None): Generator yielding the mapping values (TagSets), optionally constrained to keys starting with prefix+'.'.

• class HasTags(TagSetTyping, cs.lex.FormatableMixin, cs.deco.Promotable, cs.obj.Refreshable): A mixin for classes which have a .tags:TagSet attribute.

  The subclass may itself define its .tags instance attribute or rely on the default cached property .tags, which will return self.tags_db[self.tags_entity_key].

  Note that this mixin brings its own __new__ method which can choose a subclass based on the subclass' .TYPE_SUBNAME attribute. See the __new__ docstring.

HasTags.__delitem__(self, tag_name: str): Remove an entry from self.tags.

HasTags.__getattr__(self, tag_name: str): Convenience attributes which go via the .tags. A missing tag raises an AttributeError.

HasTags.__getitem__(self, tag_name: str): Index self.tags.

HasTags.__setitem__(self, tag_name, value, *, verbose=False): Set a tag value.

HasTags.as_dict(self): Proxy .as_dict() to self.tags.

HasTags.deref(self, tag_name, attr=None, *, subtype=None): Call .tags_db.deref(self,tag_name,...).

HasTags.format_kwargs(self): A format_kwargs method to support cs.lex.FormatableMixin.

HasTags.get(self, tag_name: str, default=None): Call .tags.get(tag_name).

HasTags.items(self): The tags items.

HasTags.print(self): The default print() runs self.printt(). This is intended to be a nice print of important stuff.

HasTags.refresh_key(self): The unique key identifying this object for use in recursive refreshes.

HasTags.refresh_last_update: The last time a refresh update time.

HasTags.setdefault(self, key, default_value): Set self[key]=default_value if key is not present.

HasTags.update(self, *update_a, **update_kw): Update the tags, tupically from a mapping or keyword arguments.

HasTags.values(self): The tags values.

• jsonable(obj, converted: Optional[dict] = None): Convert obj to a JSON encodable form. This returns obj for purely JSONable objects and a JSONable deep copy of obj if it or some subcomponent required conversion. converted is a dict mapping object ids to their converted forms to prevent loops.

• class MappingTagSets(BaseTagSets): A BaseTagSets subclass using an arbitrary mapping.

  If no mapping is supplied, a dict is created for the purpose.

  Example:

  >>> tagsets = MappingTagSets()
  >>> list(tagsets.keys())
  []
  >>> tagsets.get('foo')
  >>> tagsets['foo'] = TagSet(bah=1, zot=2)
  >>> list(tagsets.keys())
  ['foo']
  >>> tagsets.get('foo')
  TagSet:{'bah': 1, 'zot': 2}
  >>> list(tagsets.keys(prefix='foo'))
  ['foo']
  >>> list(tagsets.keys(prefix='bah'))
  []
  

MappingTagSets.__delitem__(self, name: str): Delete the TagSet named name.

MappingTagSets.__setitem__(self, name: str, te): Save te in the backend under the key name.

MappingTagSets.get(self, name: str, default=None): Get name or default.

MappingTagSets.keys(self, *, prefix: Optional[str] = None) -> Iterable[str]: Return an iterable of the keys commencing with prefix or all keys if prefix is None.

• class RegexpTagRule: A regular expression based Tag rule.

  This applies a regular expression to a string and returns inferred Tags.

RegexpTagRule.infer_tags(self, s): Apply the rule to the string s, return a list of Tags.

• selftest(argv): Run some ad hoc self tests.

• class Tag(Tag, cs.lex.FormatableMixin): A name/value pair. Each Tag has a .name (str), a .value and an optional .ontology. The name must be a dotted identifier.

  Terminology:

  • A "bare" Tag has a value of None.
  • A "naive" Tag has an ontology of None.

  The constructor for a Tag is unusual:

  • both the value and ontology are optional, defaulting to None
  • if name is a str then we always construct a new Tag with the suppplied values
  • if name is not a str it should be a Taglike object to promote; it is an error if the value parameter is not None in this case
  • an optional prefix may be supplied which is prepended to name with a dot ('.') if not empty

  The promotion process is as follows:

  • if name is a Tag subinstance then if the supplied ontology is not None and is not the ontology associated with name then a new Tag is made, otherwise the original Tag is returned unchanged
  • otherwise a new Tag is made from name using its .value and overriding its .ontology if the ontology parameter is not None

  Examples:

  >>> ont = TagsOntology({'colour.blue': TagSet(wavelengths='450nm-495nm')})
  >>> tag0 = Tag('colour', 'blue')
  >>> tag0
  Tag(name='colour',value='blue')
  >>> tag = Tag(tag0)
  >>> tag
  Tag(name='colour',value='blue')
  >>> tag = Tag(tag0, ontology=ont)
  >>> tag # doctest: +ELLIPSIS
  Tag(name='colour',value='blue',ontology=...)
  >>> tag = Tag(tag0, prefix='surface')
  >>> tag
  Tag(name='surface.colour',value='blue')
  

Tag.__init__(self, *a, **kw): Dummy __init__ to avoid FormatableMixin.__init__ because we subclass namedtuple which has no __init__.

Tag.__hash__

Tag.__str__(self): Encode name and value. A "bare" Tag (self.value is None) is just its name. Otherwise {self.name}={self.transcribe_value(self.value)}.

Tag.alt_values(self, value_tag_name=None): Return a list of alternative values for this Tag on the premise that each has a metadata entry.

Tag.basetype: The base type name for this tag. Returns None if there is no ontology.

This calls self.onotology.basetype(self.name). The basetype is the endpoint of a cascade down the defined types.

For example, this might tell us that a Tag role="Fred" has a basetype "str" by cascading through a hypothetical chain role->character->str:

type.role type=character
type.character type=str

Tag.from_arg(arg, offset=0, ontology=None): Parse a Tag from the string arg at offset (default 0). where arg is known to be entirely composed of the value, such as a command line argument.

This calls the from_str method with fallback_parse set to gather then entire tail of the supplied string arg.

Tag.from_str(s, ontology=None, fallback_parse=None): Parse s as a Tag definition. This is the inverse of Tag.__str__, and a shim for Tag.parse which checks that the entire string is consumed.

Tag.from_str2(*a, **kw): OBSOLETE version of from_str2, suggestion: Tag.parse

Obsolete name for Tag.parse.

Tag.is_valid_name(name): Test whether a tag name is valid: a dotted identifier.

Tag.key_metadata(self, key): Return the metadata definition for key.

The metadata TagSet is obtained from the ontology entry type.key_tag_name where type is the Tag's key_type and key_tag_name is the key converted into a dotted identifier by TagsOntology.value_to_tag_name.

Tag.key_type: The type name for members of this tag.

This is required if .value is a mapping.

Tag.key_typedef: The typedata definition for this Tag's keys.

This is for Tags which store mappings, for example a movie cast, mapping actors to roles.

The name of the member type comes from the key_type entry from self.typedata. That name is then looked up in the ontology's types.

Tag.matches(self, tag_name, value): Test whether this Tag matches (tag_name,value).

Tag.member_metadata(self, member_key): Return the metadata definition for self[member_key].

The metadata TagSet is obtained from the ontology entry type.member_tag_name where type is the Tag's member_type and member_tag_name is the member value converted into a dotted identifier by TagsOntology.value_to_tag_name.

Tag.member_type: The type name for members of this tag.

This is required if .value is a sequence or mapping.

Tag.member_typedef: The typedata definition for this Tag's members.

This is for Tags which store mappings or sequences, for example a movie cast, mapping actors to roles, or a list of scenes.

The name of the member type comes from the member_type entry from self.typedata. That name is then looked up in the ontology's types.

Tag.meta: Shortcut property for the metadata TagSet.

Tag.metadata(self, *, ontology=None, convert=None) -> 'TagSet': Fetch the metadata information about this specific tag value, derived through the ontology from the tag name and value. The default ontology is self.ontology.

For a scalar type (int, float, str) this is the ontology TagSet for self.value.

For a sequence (list) this is a list of the metadata for each member.

For a mapping (dict) this is mapping of key->metadata.

Tag.parse(s, offset=0, *, ontology=None, **parse_value_kw): Parse tag_name[=value] from s at offset, return (Tag,post_offset).

Parameters:

• s: the string to parse
• offset: optional offset of the parse start, default 0
• ontology: optional TagsOntology to associate with the Tag

Other keyword arguments are passed to Tag.parse_value.

Tag.parse_name(s, offset=0): Parse a tag name from s at offset: a dotted identifier.

Tag.parse_value(s, offset=0, *, extra_types=None, fallback_parse=None): Parse a value from s at offset (default 0). Return the value, or None on no data.

The optional extra_types parameter may be an iterable of (type,from_str,to_str) tuples where from_str is a function which takes a string and returns a Python object (expected to be an instance of type). The default comes from cls.EXTRA_TYPES. This supports storage of nonJSONable values in text form.

The optional fallback_parse parameter specifies a parse function accepting (s,offset) and returning (parsed,new_offset) where parsed is text from s[offset:] and new_offset is where the parse stopped. The default is cs.lex.get_nonwhite to gather nonwhitespace characters, intended to support tag_name=bare_word in human edited tag files.

The core syntax for values is JSON; value text commencing with any of '"', '[' or '{' is treated as JSON and decoded directly, leaving the offset at the end of the JSON parse.

Otherwise all the nonwhitespace at this point is collected as the value text, leaving the offset at the next whitespace character or the end of the string. The text so collected is then tried against the from_str function of each extra_types; the first successful parse is accepted as the value. If no extra type match, the text is tried against int() and float(); if one of these parses the text and str() of the result round trips to the original text then that value is used. Otherwise the text itself is kept as the value.

Tag.transcribe_value(value, extra_types=None, json_options=None): Transcribe value for use in Tag transcription.

The optional extra_types parameter may be an iterable of (type,from_str,to_str) tuples where to_str is a function which takes a string and returns a Python object (expected to be an instance of type). The default comes from cls.EXTRA_TYPES.

If value is an instance of type then the to_str function is used to transcribe the value as a str, which should not include any whitespace (because of the implementation of parse_value). If there is no matching to_str function, cls.JSON_ENCODER.encode is used to transcribe value.

This supports storage of nonJSONable values in text form.

Tag.typedef: The defining TagSet for this tag's name.

This is how its type is defined, and is obtained from: self.ontology['type.'+self.name]

Basic Tags often do not need a type definition; these are only needed for structured tag values (example: a mapping of cast members) or when a Tag name is an alias for another type (example: a cast member name might be an actor which in turn might be a person).

For example, a Tag colour=blue gets its type information from the type.colour entry in an ontology; that entry is just a TagSet with relevant information.

• tag_or_tag_value(*da, **dkw): A decorator for functions or methods which may be called as:

  func(name[,value])
  

  or as:

  func(Tag)
  

  The optional decorator argument no_self (default False) should be supplied for plain functions as they have no leading self parameter to accomodate.

  Example:

  @tag_or_tag_value
  def add(self, tag_name, value, *, verbose=None):
  

  This defines a .add() method which can be called with name and value or with single Taglike object (something with .name and .value attributes), for example:

  tags = TagSet()
  ....
  tags.add('colour', 'blue')
  ....
  tag = Tag('size', 9)
  tags.add(tag)
  

• class TagBasedTest(TagBasedTest, TagSetCriterion): A test based on a Tag.

  Attributes:

  • spec: the source text from which this choice was parsed, possibly None
  • choice: the select/reject flag, True to select
  • tag: the Tag representing the criterion
  • comparison: an indication of the test comparison

  The following comparison values are recognised:

  • None: test for the presence of the Tag
  • '=': test that the tag value equals tag.value
  • '<': test that the tag value is less than tag.value
  • '<=': test that the tag value is less than or equal to tag.value
  • '>': test that the tag value is greater than tag.value
  • '>=': test that the tag value is greater than or equal to tag.value
  • '~/': test if the tag value as a regexp is present in tag.value
  • '~': test if a matching tag value is present in tag.value

TagBasedTest.by_tag_value(tag_name, tag_value, *, choice=True, comparison='='): Return a TagBasedTest based on a Tag or tag_name,tag_value.

TagBasedTest.match_tagged_entity(self, te: 'TagSet') -> bool: Test against the Tags in tags.

Note: comparisons when self.tag.name is not in tags always return False (possibly inverted by self.choice).

TagBasedTest.parse(s, offset=0, delim=None): Parse tag_name[{<|<=|'='|'>='|>|'~'}value] and return (dict,offset) where the dict contains the following keys and values:

• tag: a Tag embodying the tag name and value
• comparison: an indication of the test comparison

• class TagFile(cs.fs.FSPathBasedSingleton, BaseTagSets): A reference to a specific file containing tags.

  This manages a mapping of name => TagSet, itself a mapping of tag name => tag value.

TagFile.__setitem__(self, name, te): Set item name to te.

TagFile.get(self, name, default=None): Get from the tagsets.

TagFile.is_modified(self): Test whether this TagSet has been modified.

TagFile.keys(self, *, prefix=None): tagsets.keys

If the options prefix is supplied, yield only those keys starting with prefix.

TagFile.load_tagsets(filepath, ontology, extra_types=None): Load filepath and return (tagsets,unparsed).

The returned tagsets are a mapping of name=>tag_name=>value. The returned unparsed is a list of (lineno,line) for lines which failed the parse (excluding the trailing newline).

TagFile.names: The names from this FSTagsTagFile as a list.

TagFile.parse_tags_line(line, ontology=None, verbose=None, extra_types=None) -> Tuple[str, cs.tagset.TagSet]: Parse a "name tags..." line as from a .fstags file, return (name,TagSet).

TagFile.save(self, extra_types=None, prune=False): Save the tag map to the tag file if modified.

TagFile.save_tagsets(filepath, tagsets, unparsed, extra_types=None, prune=False): Save tagsets and unparsed to filepath.

This method will create the required intermediate directories if missing.

This method does not clear the .modified attribute of the TagSets because it does not know it is saving to the Tagset's primary location.

TagFile.startup_shutdown(self): Save the tagsets if modified.

TagFile.tags_line(name, tags, extra_types=None, prune=False): Transcribe a name and its tags for use as a .fstags file line.

TagFile.tagsets: The tag map from the tag file, a mapping of name=>TagSet.

This is loaded on demand.

TagFile.update(self, name, tags, *, prefix=None, verbose=None): Update the tags for name from the supplied tags as for Tagset.update.

TagFile.write_tagsets(f, tagsets, unparsed, extra_types=None, prune=False): Save tagsets and unparsed to the file f.

This method does not clear the .modified attribute of the TagSets because it does not know it is saving to the Tagset's primary location.

• class TagsCommandMixin: Utility methods for cs.cmdutils.BaseCommand classes working with tags.

  Optional subclass attributes:

  • TAGSET_CRITERION_CLASS: a TagSetCriterion duck class, default TagSetCriterion. For example, cs.sqltags has a subclass with an .extend_query method for computing an SQL JOIN used in searching for tagged entities.

TagsCommandMixin.TagAddRemove

TagsCommandMixin.parse_tag_addremove(arg, offset=0): Parse arg as an add/remove tag specification of the form [-]tag_name[=value]. Return (remove,Tag).

Examples:

>>> TagsCommandMixin.parse_tag_addremove('a')
TagAddRemove(remove=False, tag=Tag(name='a',value=None))
>>> TagsCommandMixin.parse_tag_addremove('-a')
TagAddRemove(remove=True, tag=Tag(name='a',value=None))
>>> TagsCommandMixin.parse_tag_addremove('a=1')
TagAddRemove(remove=False, tag=Tag(name='a',value=1))
>>> TagsCommandMixin.parse_tag_addremove('-a=1')
TagAddRemove(remove=True, tag=Tag(name='a',value=1))
>>> TagsCommandMixin.parse_tag_addremove('-a="foo bah"')
TagAddRemove(remove=True, tag=Tag(name='a',value='foo bah'))
>>> TagsCommandMixin.parse_tag_addremove('-a=foo bah')
TagAddRemove(remove=True, tag=Tag(name='a',value='foo bah'))

TagsCommandMixin.parse_tag_choices(argv): Parse argv as an iterable of [!]tag_name[=*tag_value] Tag` additions/deletions.

TagsCommandMixin.parse_tagset_criteria(cls, argv, **ptc_kw): OBSOLETE version of parse_tagset_criteria, suggestion: TagsCommandMixin.pop_tagset_criteria

Obsolete shim for pop_tagset_criteria.

TagsCommandMixin.parse_tagset_criterion(arg, tag_based_test_class=None): Parse arg as a tag specification and return a tag_based_test_class instance via its .from_str factory method. Raises ValueError in a misparse. The default tag_based_test_class comes from cls.TAGSET_CRITERION_CLASS, which itself defaults to class TagSetCriterion.

The default TagSetCriterion.from_str recognises:

• -tag_name: a negative requirement for tag_name
• tag_name[=value]: a positive requirement for a tag_name with optional value.

TagsCommandMixin.pop_tagset_criteria(argv, tag_based_test_class=None): Parse and pop tag specifications from argv until an unparseable item is found. Return a list of the parsed criteria.

Each item is parsed via cls.parse_tagset_criterion(item,tag_based_test_class).

• class TagSet(builtins.dict, cs.dateutils.UNIXTimeMixin, TagSetTyping, cs.lex.FormatableMixin, cs.mappings.AttrableMappingMixin, cs.deco.Promotable, cs.obj.Refreshable): A setlike class collection of Tags.

  This actually subclasses dict, so a TagSet is a direct mapping of tag names to values. It accepts attribute access to simple tag values when they do not conflict with the class methods; the reliable method is normal item access.

  NOTE: iteration yields Tags, not dict keys.

  Also note that all the Tags from a TagSet share its ontology.

  Subclasses should override the set and discard methods; the dict and mapping methods are defined in terms of these two basic operations.

  TagSets have a few special properties:

  • id: a domain specific identifier; this may reasonably be None for entities not associated with database rows; the cs.sqltags.SQLTags class associates this with the database row id.
  • name: the entity's name; a read only alias for the 'name' Tag. The cs.sqltags.SQLTags class defines "log entries" as TagSets with no name.
  • unixtime: a UNIX timestamp, a float holding seconds since the UNIX epoch (midnight, 1 January 1970 UTC). This is typically the row creation time for entities associated with database rows, but usually the event time for TagSets describing an event.

  Because TagSet subclasses cs.mappings.AttrableMappingMixin you can also access tag values as attributes provided that they do not conflict with instance attributes or class methods or properties.

TagSet.__init__(self, *a, _ontology=None, **kw): Initialise the TagSet.

Parameters:

• positional parameters initialise the dict and are passed to dict.__init__
• _ontology: optional TagsOntology to use for this TagSet`
• other alphabetic keyword parameters are also used to initialise the dict and are passed to dict.__init__

TagSet.__contains__(self, tag): Test for a tag being in this TagSet.

If the supplied tag is a str then this test is for the presence of tag in the keys.

Otherwise, for each tag T in the tagset test T.matches(tag) and return True on success. The default Tag.matches method compares the tag name and if the same, returns true if tag.value is None (basic "is the tag present" test) and otherwise true if tag.value==T.value (basic "tag value equality" test).

Otherwise return False.

TagSet.__getattr__(self, attr): Support access to dotted name attributes.

The following attribute accesses are supported:

• an attribute from a superclass
• a Tag whose name is attr; return its value
• the value of self.auto_infer(attr) if that does not raise ValueError
• if self.ontology, try {type}{field} and {type}{field}s
• otherwise return self.subtags(attr) to allow access to dotted tags, provided any existing tags start with "attr."

If this TagSet has an ontology and attr looks like *typename*_*fieldname* and *typename* is a key, look up the metadata for the Tag` value and return the metadata's fieldname key. This also works for plural values.

For example if a TagSet has the tag artists=["fred","joe"] and attr is artist_names then the metadata entries for "fred" and "joe" are looked up and their artist_name tags are returned, perhaps resulting in the list ["Fred Thing","Joe Thang"].

If there are keys commencing with attr+'.' then this returns a view of those keys so that a subsequent attribute access can access one of those keys.

Otherwise, a superclass attribute access is performed.

Example of dotted access to tags like c.x:

>>> tags=TagSet(a=1,b=2)
>>> tags.a
1
>>> tags.c
Traceback (most recent call last):
    ...
AttributeError: TagSet.c
>>> tags['c.z']=9
>>> tags['c.x']=8
>>> tags
TagSet:{'a': 1, 'b': 2, 'c.z': 9, 'c.x': 8}
>>> tags.c
TagSetPrefixView:c.{'z': 9, 'x': 8}
>>> tags.c.z
9

However, this is not supported when there is a tag named 'c' because tags.c has to return the 'c' tag value:

>>> tags=TagSet(a=1,b=2,c=3)
>>> tags.a
1
>>> tags.c
3
>>> tags['c.z']=9
>>> tags.c.z
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'int' object has no attribute 'z'

TagSet.__iter__(self, prefix=None, ontology=None): Yield the tag data as Tags.

TagSet.__setattr__(self, attr, value): Attribute based Tag access.

If attr is private or is in self.__dict__ then that is updated, supporting "normal" attributes set on the instance. Otherwise the Tag named attr is set to value.

The __init__ methods of subclasses should do something like this (from TagSet.__init__) to set up additional ordinary instance attributes which are not to be treated as Tags:

self.__dict__.update(ontology=_ontology, modified=False)

TagSet.__str__(self): The TagSet suitable for writing to a tag file.

TagSet.add(self, tag_name, value, **kw): Adding a Tag calls the class set() method.

TagSet.as_dict(self): Return a dict mapping tag name to value.

TagSet.as_tags(self, prefix=None, ontology=None): Yield the tag data as Tags.

TagSet.auto: The automatic namespace. Here we can refer to dotted tag names directly as attributes.

TagSet.auto_infer(self, attr): The default inference implementation.

This should return a value if attr is inferrable and raise ValueError if not.

The default implementation returns the direct tag value for attr if present.

TagSet.csvrow: This TagSet as a list useful to a csv.writer. The inverse of from_csvrow.

TagSet.discard(self, tag_name, value, *, verbose=None): Discard the tag matching (tag_name,value). Return a Tag with the old value, or None if there was no matching tag.

Note that if the tag value is None then the tag is unconditionally discarded. Otherwise the tag is only discarded if its value matches.

TagSet.dump(self, keys=None, *, preindent=None, file=None, **pf_kwargs): OBSOLETE version of dump, suggestion: TagSet.printt

Dump a TagSet in multiline format.

Parameters:

• keys: optional iterable of Tag names to print
• file: optional keyword parameter specifying the output filelike object; the default is sys.stdout.
• preindent: optional leading indentation for the entire dump, either a str or an int indicating a number of spaces Other keyword arguments are passed to pprint.pformat.

TagSet.edit(self, editor=None, verbose=None, comments=()): Edit this TagSet.

TagSet.edit_tagsets(tes, editor=None, *, verbose=None): Edit a collection of TagSets. Return a list of (old_name,new_name,TagSet) for those which were modified.

This function supports modifying both name and Tags. The Tags are updated directly. The changed names are returning in the old_name,new_name above.

The collection tes may be either a mapping of name/key to TagSet or an iterable of TagSets. If the latter, a mapping is made based on te.name or te.id for each item te in the iterable.

TagSet.from_csvrow(csvrow): Construct a TagSet from a CSV row like that from TagSet.csvrow, being unixtime,id,name,tag[,tag,...].

TagSet.from_ini(f, section: str, missing_ok=False): Load a TagSet from a section of a .ini file.

Parameters:

• f: the .ini format file to read; an iterable of lines (eg a file object) or the name of a file to open
• section: the name of the config section from which to load the TagSet
• missing_ok: optional flag, default False; if true a missing file will return an empty TagSet instead of raising FileNotFoundError

TagSet.from_line(s, offset: int, **from_str_kw): OBSOLETE version of from_line, suggestion: TagSet.from_str

Obsolete form of TagSet.from_str.

TagSet.from_str(tags_s, *, ontology=None, extra_types=None, verbose=None): Create a new TagSet from a line of text. The line consists of a whitespace separated list of Tags.

This is the inverse of TagSet.__str__.

TagSet.from_tags(tags, _ontology=None): Make a TagSet from an iterable of Tags.

TagSet.get_arg_name(self, field_name): Override for FormattableMixin.get_arg_name: return the leading dotted identifier, which represents a tag name or prefix.

TagSet.json(self): Return a JSONable version of this TagSet.

TagSet.name: Read only name property, None if there is no 'name' tag.

TagSet.refresh_last_update: The last time a refresh update time.

TagSet.save_as_ini(self, f, section: str, config=None): Save this TagSet to the config file f as section.

If f is a string, read an existing config from that file and update the section.

TagSet.set(self, tag_name, value, *, verbose: bool): Set self[tag_name]=value. If verbose, emit an info message if this changes the previous value.

TagSet.set_from(self, other, verbose=None): Completely replace the values in self with the values from other, a TagSet or any other name=>value mapping.

This has the feature of logging changes by calling .set and .discard to effect the changes.

TagSet.subtags(self, prefix, as_tagset=False): Return TagSetPrefixView of the tags commencing with prefix+'.' with the key prefixes stripped off.

If as_tagset is true (default False) return a new standalone TagSet containing the prefixed keys.

Example:

>>> tags = TagSet({'a.b':1, 'a.d':2, 'c.e':3})
>>> tags.subtags('a')
TagSetPrefixView:a.{'b': 1, 'd': 2}
>>> tags.subtags('a', as_tagset=True)
TagSet:{'b': 1, 'd': 2}

TagSet.tag(self, tag_name, prefix=None, ontology=None): Return a Tag for tag_name, or None if missing.

Parameters:

• tag_name: the name of the Tag to create
• prefix: optional prefix; if supplied, prepend prefix+'.' to the Tag name
• ontology: optional ontology for the Tag, default self.ontology

TagSet.tag_metadata(self, tag_name, prefix=None, ontology=None, convert=None): Return a list of the metadata for the Tag named tag_name, or an empty list if the Tag is missing.

TagSet.unixtime: unixtime property, autosets to time.time() if accessed and missing.

TagSet.update(self, other=None, *, prefix=None, verbose=None, **other_kw): Update this TagSet from other or other_kw, a dict of {name:value} or an iterable of Taglike or (name,value) things.

TagSet.uuid: The TagSet's 'uuid' value as a UUID if present, otherwise None.

• class TagSetCriterion(cs.deco.Promotable): A testable criterion for a TagSet.

TagSetCriterion.TAG_BASED_TEST_CLASS

TagSetCriterion.from_arg(arg, fallback_parse=None): Prepare a TagSetCriterion from the string arg where arg is known to be entirely composed of the value, such as a command line argument.

This calls the from_str method with fallback_parse set to gather then entire tail of the supplied string arg.

TagSetCriterion.from_str(s: str, fallback_parse=None): Prepare a TagSetCriterion from the string s.

TagSetCriterion.from_str2(s, offset=0, delim=None, fallback_parse=None): Parse a criterion from s at offset and return (TagSetCriterion,offset).

This method recognises an optional leading '!' or '-' indicating negation of the test, followed by a criterion recognised by the .parse method of one of the classes in cls.CRITERION_PARSE_CLASSES.

TagSetCriterion.match_tagged_entity(self, te: 'TagSet') -> bool: Apply this TagSetCriterion to a TagSet.

TagSetCriterion.promote(obj): Promote obj into a TagSetCriterion (or subclass).

Various possibilities for obj are:

• TagSetCriterion: returned unchanged
• str: a string tests for the presence of a tag with that name and optional value;
• an object with a .choice attribute; this is taken to be a TagSetCriterion ducktype and returned unchanged
• an object with .name and .value attributes; this is taken to be Tag-like and a positive test is constructed
• Tag: an object with a .name and .value is equivalent to a positive equality TagBasedTest
• (name,value): a 2 element sequence is equivalent to a positive equality TagBasedTest

• class TagSetPrefixView(cs.lex.FormatableMixin): A view of a TagSet via a prefix.

  Access to a key k accesses the TagSet with the key prefix+'.'+k.

  This is a kind of funny hybrid of a Tag and a TagSet in that some things such as __format__ will format the Tag named prefix if it exists in preference to the subtags.

  Example:

  >>> tags = TagSet(a=1, b=2)
  >>> tags
  TagSet:{'a': 1, 'b': 2}
  >>> tags['sub.x'] = 3
  >>> tags['sub.y'] = 4
  >>> tags
  TagSet:{'a': 1, 'b': 2, 'sub.x': 3, 'sub.y': 4}
  >>> sub = tags.sub
  >>> sub
  TagSetPrefixView:sub.{'x': 3, 'y': 4}
  >>> sub.z = 5
  >>> sub
  TagSetPrefixView:sub.{'x': 3, 'y': 4, 'z': 5}
  >>> tags
  TagSet:{'a': 1, 'b': 2, 'sub.x': 3, 'sub.y': 4, 'sub.z': 5}
  

TagSetPrefixView.__getattr__(self, attr): Proxy other attributes through to the TagSet.

TagSetPrefixView.__setattr__(self, attr, value): Attribute based Tag access.

If attr is in self.__dict__ then that is updated, supporting "normal" attributes set on the instance. Otherwise the Tag named attr is set to value.

The __init__ methods of subclasses should do something like this (from TagSet.__init__) to set up the ordinary instance attributes which are not to be treated as Tags:

self.__dict__.update(ontology=_ontology, modified=False)

TagSetPrefixView.as_dict(self): Return a dict representation of this view.

TagSetPrefixView.get(self, k, default=None): Mapping get method.

TagSetPrefixView.items(self): Return an iterable of the items (Tag name, Tag).

TagSetPrefixView.keys(self): The keys of the subtags.

TagSetPrefixView.ontology: The ontology of the references TagSet.

TagSetPrefixView.setdefault(self, k, v=None): Mapping setdefault method.

TagSetPrefixView.subtags(self, subprefix): Return a deeper view of the TagSet.

TagSetPrefixView.tag: The Tag for the prefix, or None if there is no such Tag.

TagSetPrefixView.update(self, mapping): Update tags from a name->value mapping.

TagSetPrefixView.value: Return the Tag value for the prefix, or None if there is no such Tag.

TagSetPrefixView.values(self): Return an iterable of the values (Tags).

• class TagSetsSubdomain(cs.obj.SingletonMixin, cs.mappings.PrefixedMappingProxy): A view into a BaseTagSets for keys commencing with a prefix being the subdomain plus a dot ('.').

TagSetsSubdomain.TAGGED_ENTITY_FACTORY: The entity factory comes from the parent collection.

• class TagSetTyping: A mixin to support TagSet types based on their .name attribute. These see proper use in the cs.sqltags.SQLTagSets class where dereferences of tag values to other TagSets may be done. This is used by the TagSet class and its subclasses.

  The typing system for a TagSet is simple. We base the type on the .name attribute which is expected to designate this TagSet within some database uniquely, consisting of a dot separated string which we consider to have 3 parts:

  • the zone: the leftmost dotted component
  • the subname: the dotted componented between the zone and the key
  • the key: the rightmost dotted component

  The zone represents the domain where this TagSet have meaning. The subname represents a type within that domain; it may contain internal dots. The key represents a key unique within the subname type space.

  For example, a TagSet whose .name was tvdb.series.1234 would have the following properties from this mixin class:

  • .type_name: tvdb.series
  • .type_subname: series
  • .type_zone: tvdb
  • .type_key: `1234``

TagSetTyping.type_key: The type key of this entity, the final dotted component of self.name.

TagSetTyping.type_key_of(name: str): The type key of this entity name, the final dotted component.

Example:

>>> TagSetTyping.type_key_of('tvdb.series.1234')
'1234'

TagSetTyping.type_name: The database-wide type name of this entity, self.name without the final dotted component.

TagSetTyping.type_name_of(name: str): The database-wide type name of this entity name, the name without the final dotted component.

Example:

>>> TagSetTyping.type_name_of('tvdb.series.1234')
'tvdb.series'

TagSetTyping.type_parts: The (zone,subname,key) 3 tuple from self.name where the zone if the leftmost dotted component, the key is the rightmost dotted component, and the subname is the middle components.

TagSetTyping.type_parts_of(name: str) -> Tuple[str, str, str]: Return the (zone,subname,key) 3 tuple from an entity name, where the zone if the leftmost dotted component, the key is the rightmost dotted component, and the subname is the middle components.

Example:

>>> TagSetTyping.type_parts_of('tvdb.series.1234')
('tvdb', 'series', '1234')

TagSetTyping.type_reference: The foreign reference to this TagSet as a (tag_name,reference) 2-tuple. This is self.type_reference_of(self.name).

For example, the type reference to an entity named tvdb.series.1234 is ('id.tvdb.series','1234').

TagSetTyping.type_reference_apply_to(self, other): Apply a reference to self to other. This applies self.type_reference to other as a tag.

For example, adding a foreign reference for an entity named tvdb.series.1234 would set other['tvdb.zone_key']='series.1234'.

TagSetTyping.type_reference_of(name: str): Return a 2-tuple of (id.*type_name*, *type_key*)to be used as a tag name and value to annotate aTagSetto refer to an entityname`.

For example, the type reference to an entity named tvdb.series.1234 is ('id.tvdb.series','1234').

TagSetTyping.type_references(self, tags_db: 'UsesTagSets') -> Mapping[str, ForwardRef('HasTags')]: Return a dict mapping type_zone to the entity from that zone in tags_db for all tags whose tag name has the form zone.zone_key.

Parameters:

• tags_db: the HasTags from which to obtain the entities

For example, tags.type_references(sitemap,('tvdb',)) where tags had a id.tvdb.series='1234' tag would return a dict with a key of 'tvdb.series' and a corresponding TVDBSeries instance for series 1234.

TagSetTyping.type_subname: The subtype name of this entity, self.name without the first and final dotted components i.e. without the leading zone and the trailing key.

For example the .type_subname of an entity named tvdb.series.1234 is series.

TagSetTyping.type_subname_of(name: str): The subtype name of this entity name, the name without the first and final dotted components i.e. without the leading zone and the trailing key.

Example:

>>> TagSetTyping.type_subname_of('tvdb.series.1234')
'series'

TagSetTyping.type_zone: The type zone of this entity, self.name's leftmost dotted component.

TagSetTyping.type_zone_key: The type zone of this entity, self.name's second and following dotted components.

For example the .type_zone_key of an entity named tvdb.series.1234 is series.1234.

TagSetTyping.type_zone_key_of(name: str) -> str: The type zone of this entity name, the second and following dotted components.

Example:

>>> TagSetTyping.type_zone_key_of('tvdb.series.1234')
'series.1234'

TagSetTyping.type_zone_of(name: str): The type zone of this entity name, the leftmost dotted component.

For example the .type_zone_of of an entity named tvdb.series.1234 is tvdb. Example:

>>> TagSetTyping.type_zone_of('tvdb.series.1234')
'tvdb'

• class TagsOntology(cs.obj.SingletonMixin, BaseTagSets): An ontology for tag names. This is based around a mapping of names to ontological information expressed as a TagSet.

  Normally an object's tags are not a self contained repository of all the information; instead a tag just names some information.

  As a example, consider the tag colour=blue. Meta information about blue is obtained via the ontology, which has an entry for the colour blue.

  We adopt the convention that the type is just the tag name, so we obtain the metadata by calling ontology.metadata(tag) or alternatively ontology.metadata(tag.name,tag.value) being the type name and value respectively.

  The ontology itself is based around TagSets and effectively the call ontology.metadata('colour','blue') would look up the TagSet named colour.blue in the ontology.

  For a self contained dataset this means that it can be its own ontology.

  For tags associated with arbitrary objects such as the filesystem tags maintained by cs.fstags the ontology would be a separate tags collection stored in a central place.

  There are two main categories of entries in an ontology:

  • metadata: other entries named typename.value_key contains a TagSet holding metadata for a value of type typename whose value is mapped to value_key
  • types: an optional entry named type.typename contains a TagSet describing the type named typename; really this is just more metadata where the "type name" is type

  Metadata are TagSet instances describing particular values of a type. For example, the metadata TagSet for the Tag colour="blue":

  colour.blue
    url="https://en.wikipedia.org/wiki/Blue"
    wavelengths="450nm-495nm"
  

  Some metadata associated with the Tag actor="Scarlett Johansson":

  actor.scarlett_johansson
    role=["Black Widow (Marvel)"]
  character.marvel.black_widow
    fullname=["Natasha Romanov"]
  

  The tag values are lists above because an actor might play many roles, etc.

  There's a default convention for converting human descriptions such as the role string "Black Widow (Marvel)" to its metadata.

  • the value "Black Widow (Marvel)" if converted to a key by the ontology method value_to_tag_name; it moves a bracket suffix such as (Marvel) to the front as a prefix marvel. and downcases the rest of the string and turns spaces into underscores. This yields the value key marvel.black_widow.
  • the type is role, so the ontology entry for the metadata is role.marvel.black_widow

  This requires type information about a role. Here are some type definitions supporting the above metadata:

  type.person
    type=str
    description="A person."
  type.actor
    type=person
    description="An actor's stage name."
  type.character
    type=str
    description="A person in a story."
  type.role
    type_name=character
    description="A character role in a performance."
  
  type.cast
    type=dict
    key_type=actor
    member_type=role
    description="Cast members and their roles."
  

  The basic types have their Python names: int, float, str, list, dict, date, datetime. You can define subtypes of these for your own purposes as illustrated above.

  For example:

  type.colour type=str description="A hue."
  

  which subclasses str.

  Subtypes of list include a member_type specifying the type for members of a Tag value:

  type.scene type=list member_type=str description="A movie scene."
  

  Subtypes of dict include a key_type and a member_type specifying the type for keys and members of a Tag value:

  Accessing type data and metadata:

  A TagSet may have a reference to a TagsOntology as .ontology and so also does any of its Tags.

TagsOntology.__bool__(self): Support easy ontology or some_default tests, since ontologies are broadly optional.

TagsOntology.__delitem__(self, name): Delete the entity named name.

TagsOntology.__getitem__(self, name): Fetch tags for the entity named name.

TagsOntology.__setitem__(self, name, tags): Apply tags to the entity named name.

TagsOntology.add_tagsets(self, tagsets: cs.tagset.BaseTagSets, match, unmatch=None, index=0): Insert a _TagsOntology_SubTagSets at index in the list of _TagsOntology_SubTagSetses.

The new _TagsOntology_SubTagSets instance is initialised from the supplied tagsets, match, unmatch parameters.

TagsOntology.as_dict(self): Return a dict containing a mapping of entry names to their TagSets.

TagsOntology.basetype(self, typename): Infer the base type name from a type name. The default type is 'str', but any type which resolves to one in self.BASE_TYPES may be returned.

TagsOntology.by_type(self, type_name, with_tagsets=False): Yield keys or (key,tagset) of type type_name i.e. all keys commencing with type_name..

TagsOntology.convert_tag(self, tag): Convert a Tag's value accord to the ontology. Return a new Tag with the converted value or the original Tag unchanged.

This is primarily aimed at things like regexp based autotagging, where the matches are all strings but various fields have special types, commonly ints or dates.

TagsOntology.edit_indices(self, indices, prefix=None): Edit the entries specified by indices. Return TagSets for the entries which were changed.

TagsOntology.from_match(tagsets, match, unmatch=None): Initialise a SubTagSets from tagsets, match and optional unmatch.

Parameters:

• tagsets: a TagSets holding ontology information
• match: a match function used to choose entries based on a type name
• unmatch: an optional reverse for match, accepting a subtype name and returning its public name

If match is None then tagsets will always be chosen if no prior entry matched.

Otherwise, match is resolved to a function match-func(type_name) which returns a subtype name on a match and a false value on no match.

If match is a callable it is used as match_func directly.

if match is a list, tuple or set then this method calls itself with (tagsets,submatch) for each member submatch if match.

If match is a str, if it ends in a dot '.', dash '-' or underscore '_' then it is considered a prefix of type_name and the returned subtype name is the text from type_name after the prefix othwerwise it is considered a full match for the type_name and the returns subtype name is type_name unchanged. The match string is a simplistic shell style glob supporting * but not ? or [seq].

The value of unmatch is constrained by match. If match is None, unmatch must also be None; the type name is used unchanged. If match is callable, unmatchmust also be callable; it is expected to reversematch`.

Examples:

>>> from cs.sqltags import SQLTags
>>> from os.path import expanduser as u
>>> # an initial empty ontology with a default in memory mapping
>>> ont = TagsOntology()
>>> # divert the types actor, role and series to my media ontology
>>> ont.add_tagsets(
...     SQLTags(u('~/var/media-ontology.sqlite')),
...     ['actor', 'role', 'series'])
>>> # divert type "musicbrainz.recording" to mbdb.sqlite
>>> # mapping to the type "recording"
>>> ont.add_tagsets(SQLTags(u('~/.cache/mbdb.sqlite')), 'musicbrainz.')
>>> # divert type "tvdb.actor" to tvdb.sqlite
>>> # mapping to the type "actor"
>>> ont.add_tagsets(SQLTags(u('~/.cache/tvdb.sqlite')), 'tvdb.')

TagsOntology.get(self, name, default=None): Fetch the entity named name or default.

TagsOntology.items(self): Yield (entity_name,tags) for all the items in each subtagsets.

TagsOntology.keys(self): Yield entity names for all the entities.

TagsOntology.metadata(self, type_name, value, *, convert=None): Return the metadata TagSet for type_name and value. This implements the mapping between a type's value and its semantics.

The optional parameter convert may specify a function to use to convert value to a tag name component to be used in place of self.value_to_tag_name (the default).

For example, if a TagSet had a list of characters such as:

character=["Captain America (Marvel)","Black Widow (Marvel)"]

then these values could be converted to the dotted identifiers character.marvel.captain_america and character.marvel.black_widow respectively, ready for lookup in the ontology to obtain the "metadata" TagSet for each specific value.

TagsOntology.startup_shutdown(self): Open all the subTagSets and close on exit.

TagsOntology.subtype_name(self, type_name): Return the type name for use within self.tagsets from type_name. Returns None if this is not a supported type_name.

TagsOntology.type_name(self, subtype_name): Return the external type name from the internal subtype_name which is used within self.tagsets.

TagsOntology.type_names(self): Return defined type names i.e. all entries starting type..

TagsOntology.type_values(self, type_name, value_tag_name=None): Yield the various defined values for type_name. This is useful for types with enumerated metadata entries.

For example, if metadata entries exist as foo.bah and foo.baz for the type_name 'foo' then this yields 'bah' and 'baz'.`

Note that this looks for a Tag for the value, falling back to the entry suffix if the tag is not present. That tag is normally named value (from DEFAULT_VALUE_TAG_NAME) but may be overridden by the value_tag_name parameter. Also note that normally it is desireable that the value convert to the suffix via the value_to_tag_name method so that the metadata entry can be located from the value.

TagsOntology.typedef(self, type_name): Return the TagSet defining the type named type_name.

TagsOntology.types(self): Generator yielding defined type names and their defining TagSet.

TagsOntology.value_to_tag_name(value): Convert a tag value to a tagnamelike dotted identifierish string for use in ontology lookup. Raises ValueError for unconvertable values.

We are allowing dashes in the result (UUIDs, MusicBrainz discids, etc).

ints are converted to str.

Strings are converted as follows:

• a trailing (.*) is turned into a prefix with a dot, for example "Captain America (Marvel)" becomes "Marvel.Captain America".
• the string is split into words (nonwhitespace), lowercased and joined with underscores, for example "Marvel.Captain America" becomes "marvel.captain_america".

• class TagsOntologyCommand(cs.cmdutils.BaseCommand): A command line for working with ontology types.

  Usage summary:

  Usage: tagsontology [common-options...] subcommand [options...]
    A command line for working with ontology types.
    Subcommands:
      edit [common-options...] [{/name-regexp | entity-name}]
        Edit entities.
        With no arguments, edit all the entities.
        With an argument starting with a slash, edit the entities
        whose names match the regexp.
        Otherwise the argument is expected to be an entity name;
        edit the tags of that entity.
      help [common-options...] [-l] [-s] [subcommand-names...]
        Print help for subcommands.
        This outputs the full help for the named subcommands,
        or the short help for all subcommands if no names are specified.
        Options:
          -l  Long listing.
          -r  Recurse into subcommands.
          -s  Short listing.
      info [common-options...] [field-names...]
        Recite general information.
        Explicit field names may be provided to override the default listing.
      meta [common-options...] tag=value
      repl [common-options...]
        Run a REPL (Read Evaluate Print Loop), an interactive Python prompt.
        Options:
          --banner banner  Banner.
      shell [common-options...]
        Run a command prompt via cmd.Cmd using this command's subcommands.
      type [common-options...]
          With no arguments, list the defined types.
        type [common-options...] type_name
          With a type name, print its `Tag`s.
        type [common-options...] type_name edit
          Edit the tags defining a type.
        type [common-options...] type_name edit meta_names_pattern...
          Edit the tags for the metadata names matching the
          meta_names_patterns.
        type [common-options...] type_name list
        type [common-options...] type_name ls
          List the metadata names for this type and their tags.
        type [common-options...] type_name + entity_name [tags...]
          Create type_name.entity_name and apply the tags.
  

TagsOntologyCommand.cmd_edit(self, argv): Usage: {cmd} [{{/name-regexp | entity-name}}] Edit entities. With no arguments, edit all the entities. With an argument starting with a slash, edit the entities whose names match the regexp. Otherwise the argument is expected to be an entity name; edit the tags of that entity.

TagsOntologyCommand.cmd_meta(self, argv): Usage: {cmd} tag=value

TagsOntologyCommand.cmd_type(self, argv): Usage: {cmd} With no arguments, list the defined types. {cmd} type_name With a type name, print its Tags. {cmd} type_name edit Edit the tags defining a type. {cmd} type_name edit meta_names_pattern... Edit the tags for the metadata names matching the meta_names_patterns. {cmd} type_name list {cmd} type_name ls List the metadata names for this type and their tags. {cmd} type_name + entity_name [tags...] Create type_name.entity_name and apply the tags.

TagsOntologyCommand.run_context(self): Open self.options.ontology during commands.

• class UsesTagSets: A mixin to support classes which use a BaseTagSets to store their data.

  A typical use subclasses cs.sqltags.UsesSQLTags, a subclass of this which uses an SQLTags as the storage backend.

  The meaning of the type zone, subname and key are as described for the TagSetTyping class.

  Subclasses must define the following class attributes:

  • TYPE_ZONE: the type zone identifying entities in the larger BaseTagSets data
  • HasTagsClass: a subclass of HasTags which represents data entities

  This mixin requires the subclass or its instances to provide:

  This mixin provides:

  • a __getitem__ method: accepting a (subname,key) 2-tuple and returning the appropriate instance of the HasTagSetsClass

UsesTagSets.__getitem__(self, index: Union[str, Tuple[str, Union[str, int]], Tuple[str, str, Union[str, int]]]) -> cs.tagset.HasTags: Fetch the HasTags instance for the supplied index.

The meaning of the type zone, subname and key are as described for the TagSetTyping class.

The index may take the following forms:

• str: a string which will be split into subname and key for use in self.TYPE_ZONE
• (subname,key): a 2-tuple of the type subname and key in self.TYPE_ZONE the subname make also be a subclass of self.HasTagsClass
• (zone,subname,key): a 3-tuple of the type zone, subname and key The subname may also be a class (normally a subclass of HasTags, usually a subclass of type(self).HasTagsClass); in this case the subname will be taken from type(self).TYPE_SUBNAME attribute. The key may also be an int or a uuid.UUID, in which case it will be used as str(key).

Examples:

# the HasTags subclass Artist, and the UsesTagSets
# subclass MBDB which hold MusicbrainzNG information
from cs.cdrip import Artist, MBDB
mbdb = MBDB()

# Various indices obtaining the record for Jon Cleary,
# whose key is 'mbdb.artist.a417f0e5-2c14-445a-9a07-5a7ad2bdeafa'

# the subname.key as a single string
artist = mbdb['artist.a417f0e5-2c14-445a-9a07-5a7ad2bdeafa']

# the subname and key in a 2-tuple
artist = mbdb['artist', 'a417f0e5-2c14-445a-9a07-5a7ad2bdeafa']

# the record but not from the default MBDB zonne
artist = mbdb['mbdb2', 'artist', 'a417f0e5-2c14-445a-9a07-5a7ad2bdeafa']

# the preferred way to obtain it, using the entity type
artist = mbdb[Artist, 'a417f0e5-2c14-445a-9a07-5a7ad2bdeafa']

# or if you're working with UUIDs
artist_uuid = UUID('a417f0e5-2c14-445a-9a07-5a7ad2bdeafa')
artist = mbdb[Artist, artist_uuid]

UsesTagSets.by_entity_id(entity_id: str) -> cs.tagset.HasTags: Return the HasTags instance corresponding to entity_id from the full tb Raise ValueError is entity_id cannot be parsed by TagSetTyping.type_parts_of. Raise KeyError if there is no UsesTagSets instance for the zone.

UsesTagSets.deref(self, tagged: cs.tagset.HasTags, tag_name: str, attr: Optional[str] = None, *, subtype: Optional[str] = None): Call self.tagsets.deref on tagged.tags and promote the result to use our HasTags instances.

UsesTagSets.find(self, *criteria, **crit_kw) -> List[cs.tagset.HasTags]: Find entities in the database.

This runs a find of the BaseTagSets and returns the associated HasTagSetsClass instances.

UsesTagSets.keys(self, subname=None): Return the keys from self.tagsets as (subname,type_key) 2-tuples suitable as indices of self. If subname is not None, restrict the keys to those with that subname.

UsesTagSets.tagged(self, te: cs.tagset.TagSet) -> cs.tagset.HasTags: Promote te to a HasTags in this zone. Return a self.HasTagSetsClass instance tagged with te.

UsesTagSets.zone_entity(self, zone: str) -> 'HasTags': Return the HasTags entity associated with a per-type-zone key. For example, self.zone_entity('tvdb') would return the entity for tvdb.tvdb_id where tvdb_id comes from self['tvdb.id'].

Release Log

Release 20260531:

• New TagSetTyping mixin for TagSets providing .type_name, .type_key, .type_zone and .type_subname properties based on partitioning .name into zone.type_subname.key; inherited by TagSet.
• New HasTags mixin for classes whose instances have a .tags attribute which is a TagSet, proxying several mapping methods .deref, and getattr to the .tags.
• BaseTagSets: new deref(TagSet) method to dereference values in a TagSet's tags to their corresponding TagSets.
• New UsesTagSets, the bulk of UsesSQLTags, deref which promotes the result of BaseTagSets.deref and relies on subclasses to provide a .find(), such as SQLTags.find.
• TagSet: drop get_value() and get_format_attribute().
• New TagSet.json() and HasTags.json() methods, usable as format conversions.
• New HasTags.printt() method calling cs.lex.printt().
• TagSet: new printt() method.
• jsonable: support transcribe datetime.date.
• tagset,fstags,sqltags: make _id only special to SQLTagSet (the db row id), drop all mentions elsewhere.
• TagSet.dump: make as obsolete, prefer TagSet.printt.
• TagSet and HasTags:: make Refreshable, drop the .is_stale() method, superceded by .refresh_needed().
• TagFile.save_tagset: have atomic_filename fall back to overwrite on PermissionError, uses new write_tagsets class method.
• HasTags: new .print() method for a nice summary, default calls .printt().
• Many other small changes.

Release 20250528:

• Some refactors and small fixes.
• Tag: rename Tag.from_str2 to Tag.parse, drop offset parameter of Tag.from_str.

Release 20250306: TagFile.save_tagsets: use atomic_filename to write the tag file.

Release 20250103: Replace TagSet.from_line with TagSet.from_str, leave @OBSOLETE hook behind.

Release 20241007: Tagset._Auto: act much more like a mapping.

Release 20241005: _FormatStringTagProxy: give it a format method which formats the proxied tag's value.

Release 20240422.2: jsonable: use obj.for_json() if available.

Release 20240422.1: jsonable: convert pathlib.PurePath to str, hoping this isn't too open ended a can of worms.

Release 20240422:

• New jsonable(obj) function to return a deep copy of obj which can be transcribed as JSON.
• Tag.transcribe_value: pass jsonable(value) to the JSON encoder, drop special checks now done by jsonable().
• Tag.str: do not catch TypeError any more, was embedding Python repr()s in .fstags files - now Tag.transcribe_value() does the correct thing where that is possible.

Release 20240316: Fixed release upload artifacts.

Release 20240305:

• Tag.from_str2: make the ontology optional.
• TagSetPrefixView: provide len() and update().

Release 20240211:

• TagFile.parse_tag_line: recognise dotted_identifiers directly, avoids misparsing bare "nan" as float NaN.
• Tag.parse_value: BUGFIX parse - always to the primary types first (int, float) before trying any funny extra types.

Release 20240201: TagsOntology.metadata: actually call the .items() method!

Release 20231129:

• TagSet.getattr: rework the attribute lookup with greater precision.
• TagSetPrefixView.getattr: if the attribute is not there, raise Attribute error, do not try to fall back to something else.
• TagSet: drop ATTRABLE_MAPPING_DEFAULT=None, caused far more confusion that it was worth.

Release 20230612:

• TagFile.save_tagsets: catch and warn about exceptions from update_mapping[key].update, something is wrong with my SQLTags usage.
• TagFile.save_tagsets: update_mapping: do not swallow AttributeError.

Release 20230407: Move the (optional) ORM open/close from FSTags.startup_shutdown to TagFile.save, greatly shortens the ORM lock.

Release 20230212: Mark TagSetCriterion as Promotable.

Release 20230210:

• TagFile: new optional update_mapping secondary mapping to which to mirror file tags, for example to an SQLTags.
• New .uuid:UUID property returning the UUID for the tag named 'uuid' or None.

Release 20230126: New TagSet.is_stale() method based on .expiry attribute, intended for TagSets which are caches of other primary data.

Release 20221228:

• TagFile: drop _singleton_key, FSPathBasedSingleton provides a good default.
• TagFile.save_tagsets,tags_line: new optional prune=False parameter to drop empty top level dict/lists.
• TagFile.save: plumb prune=False parameter.

Release 20220806: New TagSetCriterion.promote(obj)->TagSetCriterion class method.

Release 20220606:

• Tag.parse_value: bugfix parse of float.
• TagSet.edit: accept optional comments parameter with addition header comment lines, be more tolerant of errors, avoid losing data on error.

Release 20220430:

• TagSetPrefixView: new as_dict() method.
• TagSetPrefixView.str: behave like TagSet.str.
• TagFile.save_tagsets: do not try to save if the file is missing and the tagsets are empty.
• New TagSet.from_tags(tags) factory to make a new TagSet from an iterable of tags.
• TagSetPrefixView: add .get and .setdefault mapping methods.
• RegexpTagRule: accept optional tag_prefix parameter.
• Tagset: new from_ini() and save_as_ini() methods to support cs.timeseries config files, probably handy elsewhere.

Release 20220311: Assorted internal changes.

Release 20211212:

• Tag: new fallback_parse parameter for value parsing, default get_nonwhite.
• Tag: new from_arg factory with fallback_parse grabbing the whole string for command line arguments, thus supporting unquoted strings for ease of use.
• TagSetCriterion: new optional fallback_parse parameter and from_arg method as for the Tag factories.
• Tag.transcribe_value: accept optional json_options to control the JSON encoder, used for human friendly multiline edits in cs.app.tagger.
• Rename edit_many to edit_tagsets for clarity.
• TagsOntology: new type_values method to return values for a type (derived from their metadata entries).
• Tag: new alt_values method returning its TagsOntology.type_values.
• (Internal) New _FormatStringTagProxy which proxies a Tag but uses str(self.__proxied.value) for str to support format strings.
• (Internal) TagSet.get_value: if arg_name matches a Tag, return a _FormatStringTagProxy.
• Tag.new: accept (tag_name,value) or (Tag) as initialisation parameters.

Release 20210913:

• TagSet.get_value: raise KeyError in strict mode, leave placeholder otherwise.
• Other small changes.

Release 20210906: Many many updates; some semantics have changed.

Release 20210428: Bugfix TagSet.set: internal in place changes to a complex tag value were not noticed, causing TagFile to not update on shutdown.

Release 20210420:

• TagSet: also subclass cs.dateutils.UNIXTimeMixin.
• Various TagSetNamespace updates and bugfixes.

Release 20210404: Bugfix TagBasedTest.COMPARISON_FUNCS["="]: if cmp_value is None, return true (the tag is present).

Release 20210306:

• ExtendedNamespace,TagSetNamespace: move the .[:alpha:]* attribute support from ExtendedNamespace to TagSetNamespace because it requires Tags.
• TagSetNamespace.getattr: new _i, _s, _f suffixes to return int, str or float tag values (or None); fold _lc in with these.
• Pull most of TaggedEntity out into TaggedEntityMixin for reuse by domain specific tagged entities.
• TaggedEntity: new .set and .discard methods.
• TaggedEntity: new as_editable_line, from_editable_line, edit and edit_entities methods to support editing entities using a text editor.
• ontologies: type entries are now prefixed with "type." and metadata entries are prefixed with "meta."; provide a worked ontology example in the introduction and improve related docstrings.
• TagsOntology: new .types(), .types_names(), .meta(type_name,value), .meta_names() methods.
• TagsOntology.getitem: create missing TagSets on demand.
• New TagsOntologyCommand, initially with a "type [type_name [{edit|list}]]" subcommand, ready for use as the cmd_ont subcommand of other tag related commands.
• TagSet: support initialisation like a dict including keywords, and move the ontology parameter to _onotology.
• TagSet: include AttrableMappingMixin to enable attribute access to values when there is no conflict with normal methods.
• UUID encode/decode support.
• Honour $TAGSET_EDITOR or $EDITOR as preferred interactive editor for tags.
• New TagSet.subtags(prefix) to extract a subset of the tags.
• TagsOntology.value_metadata: new optional convert parameter to override the default "convert human friendly name" algorithm, particularly to pass convert=str to things which are already the basic id.
• Rename TaggedEntity to TagSet.
• Rename TaggedEntities to TagSets.
• TagSet: new csvrow and from_csvrow methods imported from obsolete TaggedEntityMixin class.
• Move BaseTagFile from cs.fstags to TagFile in cs.tagset.
• TagSet: support access to the tag "c.x" via attributes provided there is no "c" tag in the way.
• TagSet.unixtime: implement the autoset-to-now semantics.
• New as_timestamp(): convert date, datetime, int or float to a UNIX timestamp.
• Assorted docstring updates and bugfixes.

Release 20200716:

• Update for changed cs.obj.SingletonMixin API.
• Pull in TaggedEntity from cs.sqltags and add the .csvrow property and the .from_csvrow factory.

Release 20200521.1: Fix DISTINFO.install_requires, drop debug import.

Release 20200521:

• New ValueDetail and KeyValueDetail classes for returning ontology information; TagInfo.detail now returns a ValueDetail for scalar types, a list of ValueDetails for sequence types and a list of KeyValueDetails for mapping types; drop various TagInfo mapping/iterable style methods, too confusing to use.
• Plumb ontology parameter throughout, always optional.
• Drop TypedTag, Tags now use ontologies for this.
• New TagsCommandMixin to support BaseCommands which manipulate Tags.
• Many improvements and bugfixes.

Release 20200318:

• Note that the TagsOntology stuff is in flux and totally alpha.
• Tag.prefix_name factory returning a new tag if prefix is not empty, ptherwise self.
• TagSet.update: accept an optional prefix for inserting "foreign" tags with a distinguishing name prefix.
• Tag.as_json: turn sets and tuples into lists for encoding.
• Backport for Python < 3.7 (no fromisoformat functions).
• TagSet: drop unused and illplaced .titleify, .episode_title and .title methods.
• TagSet: remove "defaults", unused.
• Make TagSet a direct subclass of dict, adjust uses of .update etc.
• New ExtendedNamespace class which is a SimpleNamespace with some inferred attributes and a partial mapping API (keys and getitem).
• New TagSet.ns() returning the Tags as an ExtendedNamespace, which doubles as a mapping for str.format_map; TagSet.format_kwargs is now an alias for this.
• New Tag.from_string factory to parse a str into a Tag.
• New TagsOntology and TypedTag classes to provide type and value-detail information; very very alpha and subject to change.

Release 20200229.1: Initial release: pull TagSet, Tag, TagChoice from cs.fstags for independent use.