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"""This is version 0.7 of Philip J. Eby's simplegeneric module
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(http://pypi.python.org/pypi/simplegeneric), patched to work with Python 3,
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which doesn't support old-style classes.
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"""
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#Name: simplegeneric
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#Version: 0.7
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#Summary: Simple generic functions (similar to Python's own len(), pickle.dump(), etc.)
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#Home-page: http://pypi.python.org/pypi/simplegeneric
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#Author: Phillip J. Eby
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#Author-email: peak@eby-sarna.com
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#License: PSF or ZPL
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__all__ = ["generic"]
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try:
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from types import ClassType, InstanceType
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except ImportError:
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classtypes = type
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else:
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classtypes = type, ClassType
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def generic(func):
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"""Create a simple generic function"""
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_sentinel = object()
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def _by_class(*args, **kw):
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cls = args[0].__class__
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for t in type(cls.__name__, (cls,object), {}).__mro__:
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f = _gbt(t, _sentinel)
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if f is not _sentinel:
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return f(*args, **kw)
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else:
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return func(*args, **kw)
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_by_type = {object: func}
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try:
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_by_type[InstanceType] = _by_class
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except NameError: # Python 3
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pass
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_gbt = _by_type.get
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def when_type(*types):
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"""Decorator to add a method that will be called for the given types"""
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for t in types:
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if not isinstance(t, classtypes):
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raise TypeError(
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"%r is not a type or class" % (t,)
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)
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def decorate(f):
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for t in types:
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if _by_type.setdefault(t,f) is not f:
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raise TypeError(
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"%r already has method for type %r" % (func, t)
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)
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return f
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return decorate
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_by_object = {}
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_gbo = _by_object.get
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def when_object(*obs):
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"""Decorator to add a method to be called for the given object(s)"""
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def decorate(f):
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for o in obs:
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if _by_object.setdefault(id(o), (o,f))[1] is not f:
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raise TypeError(
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"%r already has method for object %r" % (func, o)
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)
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return f
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return decorate
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def dispatch(*args, **kw):
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f = _gbo(id(args[0]), _sentinel)
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if f is _sentinel:
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for t in type(args[0]).__mro__:
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f = _gbt(t, _sentinel)
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if f is not _sentinel:
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return f(*args, **kw)
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else:
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return func(*args, **kw)
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else:
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return f[1](*args, **kw)
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dispatch.__name__ = func.__name__
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dispatch.__dict__ = func.__dict__.copy()
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dispatch.__doc__ = func.__doc__
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dispatch.__module__ = func.__module__
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dispatch.when_type = when_type
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dispatch.when_object = when_object
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dispatch.default = func
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dispatch.has_object = lambda o: id(o) in _by_object
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dispatch.has_type = lambda t: t in _by_type
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return dispatch
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def test_suite():
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import doctest
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return doctest.DocFileSuite(
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'README.txt',
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optionflags=doctest.ELLIPSIS|doctest.REPORT_ONLY_FIRST_FAILURE,
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)
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