As I can see from code public_factory() returns a function that instantiate
a given class. I can not understand why this can be useful. Why we can't
just instantiate class directly as Mapper(...)? Could you please, explain.
This is need for preparation of pull request for Spyne (which integrates
with SQLAlchemy, but does not support custom mappers).
mapper = public_factory(Mapper, ".orm.mapper")
def public_factory(target, location):
"""Produce a wrapping function for the given cls or classmethod.
Rationale here is so that the __init__ method of the
class can serve as documentation for the function.
"""
if isinstance(target, type):
fn = target.__init__
callable_ = target
doc = "Construct a new :class:`.%s` object. \n\n"\
"This constructor is mirrored as a public API function; see
:func:`~%s` "\
"for a full usage and argument description." % (
target.__name__, location, )
else:
fn = callable_ = target
doc = "This function is mirrored; see :func:`~%s` "\
"for a description of arguments." % location
location_name = location.split(".")[-1]
spec = compat.inspect_getfullargspec(fn)
del spec[0][0]
metadata = format_argspec_plus(spec, grouped=False)
metadata['name'] = location_name
code = """\
def %(name)s(%(args)s):
return cls(%(apply_kw)s)
""" % metadata
env = {'cls': callable_, 'symbol': symbol}
exec(code, env)
decorated = env[location_name]
decorated.__doc__ = fn.__doc__
if compat.py2k or hasattr(fn, '__func__'):
fn.__func__.__doc__ = doc
else:
fn.__doc__ = doc
return decorated
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