cs-py-func 20181231

Convenience facilities related to Python functions.

• funccite: cite a function (name and code location)
• @prop: replacement for @property which turns internal AttributeErrors into RuntimeErrors
• some decorators to verify the return types of functions

Function callmethod_if(o, method, default=None, a=None, kw=None)

Call the named method on the object o if it exists.

If it does not exist, return default (which defaults to None). Otherwise call getattr(o, method)(*a, **kw). a defaults to (). kw defaults to {}.

Function derived_from(property_name)

A property which must be recomputed if the revision of another property exceeds the snapshot revision.

Function derived_property(func, original_revision_name='_revision', lock_name='_lock', property_name=None, unset_object=None)

A property which must be recomputed if the reference revision (attached to self) exceeds the snapshot revision.

Function funccite(func)

Return a citation for a function (name and code location).

Function funcname(func)

Return a name for the supplied function func. Several objects do not have a name attribute, such as partials.

Function prop(func)

A substitute for the builtin @property.

The builtin @property decorator lets internal AttributeErrors escape. While that can support properties that appear to exist conditionally, in practice this is almost never what I want, and it masks deeper errors. Hence this wrapper for @property that transmutes internal AttributeErrors into RuntimeErrors.

Function returns_bool(func)

Decorator for functions which should return Booleans.

Function returns_str(func)

Decorator for functions which should return strings.

Function returns_type(func, basetype)

Decrator which checks that a function returns values of type basetype.

Function yields_str(func)

Decorator for generators which should yield strings.

Function yields_type(func, basetype)

Decorator which checks that a generator yields values of type basetype.