StrictYAML

StrictYAML is a type-safe YAML parser that parses a restricted subset of the YAML specificaton.

Priorities:

Readability of YAML.
Ease of use of API.
Secure by default, strict validation of markup and straightforward type casting.
Clear, readable exceptions with code snippets and line numbers.
Acting as a near-drop in replacement for pyyaml, ruamel.yaml or poyo.
Ability to read in (commented) YAML and write it out again with comments preserved.
Letting you worry about more interesting things than parsing or writing config files.
Not speed, currently, although if writing optimized C is your thing, please help.

Simple example:

# All about the character
name: Ford Prefect
age: 42
possessions:
- Towel

Default parse result:

>>> strictyaml.load(yaml_str)
YAML(OrderedDict([('name', 'Ford Prefect'), ('age', '42'), ('possessions', ['Towel'])]))

>>> strictyaml.load(yaml_str).data    # All data is string, list or OrderedDict
OrderedDict([('name', 'Ford Prefect'),
          ('age', '42'),
          ('possessions', ['Towel'])])

Using a schema:

>>> from strictyaml import load, Map, Str, Int, Seq, YAMLError
>>> schema = Map({"name": Str(), "age": Int(), "possessions": Seq(Str())})
>>> person = load(yaml_str, schema)
>>> person.data == {"name": "Ford Prefect", "age": 42, "possessions": ["Towel", ]}     # 42 is now an int
True

A YAMLError will be raised if there are syntactic problems, violations of your schema or use of disallowed YAML features:

# All about the character
name: Ford Prefect
age: 42

>>> try:
...     person = load(yaml_str, schema)
... except YAMLError as error:
...     print(error)

while parsing a mapping
  in "<unicode string>", line 1, column 1:
    # All about the character
    ^ (line: 1)
required key(s) 'possessions' not found
  in "<unicode string>", line 3, column 1:
    age: '42'
    ^ (line: 3)

If parsed correctly you can modify values and write out the YAML with comments preserved:

>>> person['age'] = 43
>>> print(person.as_yaml())
# All about the character
name: Ford Prefect
age: 43
possessions:
- Towel

As well as look up line numbers:

>>> person['possessions'][0].start_line
5

All other features are documented using the example driven documentation.

Install It

$ pip install strictyaml

FAQ

From learning programmers:

If you’re looking at this and thinking “why not do/use X instead?” that’s a healthy response, and you deserve answers. These are probably the questions you’re asking:

Breaking changes

0.5: Data is now parsed by default as a YAML object instead of directly to dict/list. To get dict/list and ordinary values as before, get yaml_object.data.

0.7: Roundtripping now requires that you only assign YAML objects to index: e.g. yaml_object[‘x’] = another_yaml_obj

Contributors

@gvx
@AlexandreDecan
@lots0logs
@tobbez

Metadata

Release files for strictyaml 0.11.1

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Source distribution (sdist)

Source distribution for strictyaml 0.11.1
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Release files / strictyaml-0.11.1.tar.gz

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