simplegeneric.py
139 lines
| 2.9 KiB
| text/x-python
|
PythonLexer
ville
|
r988 | #Name: simplegeneric | ||
#Version: 0.6 | ||||
#Summary: Simple generic functions (similar to Python's own len(), pickle.dump(), etc.) | ||||
#Home-page: http://cheeseshop.python.org/pypi/simplegeneric | ||||
#Author: Phillip J. Eby | ||||
#Author-email: peak@eby-sarna.com | ||||
#License: PSF or ZPL | ||||
# This is version 0.6 of Philip J. Eby's simplegeneric module | ||||
# (http://cheeseshop.python.org/pypi/simplegeneric) patched to work | ||||
# with Python 2.3 (which doesn't support assigning to __name__) | ||||
__all__ = ["generic"] | ||||
from types import ClassType, InstanceType | ||||
classtypes = type, ClassType | ||||
def generic(func): | ||||
"""Create a simple generic function""" | ||||
_sentinel = object() | ||||
def _by_class(*args, **kw): | ||||
cls = args[0].__class__ | ||||
for t in type(cls.__name__, (cls,object), {}).__mro__: | ||||
f = _gbt(t, _sentinel) | ||||
if f is not _sentinel: | ||||
return f(*args, **kw) | ||||
else: | ||||
return func(*args, **kw) | ||||
_by_type = {object: func, InstanceType: _by_class} | ||||
_gbt = _by_type.get | ||||
def when_type(t): | ||||
"""Decorator to add a method that will be called for type `t`""" | ||||
if not isinstance(t, classtypes): | ||||
raise TypeError( | ||||
"%r is not a type or class" % (t,) | ||||
) | ||||
def decorate(f): | ||||
if _by_type.setdefault(t,f) is not f: | ||||
raise TypeError( | ||||
"%r already has method for type %r" % (func, t) | ||||
) | ||||
return f | ||||
return decorate | ||||
_by_object = {} | ||||
_gbo = _by_object.get | ||||
def when_object(o): | ||||
"""Decorator to add a method that will be called for object `o`""" | ||||
def decorate(f): | ||||
if _by_object.setdefault(id(o), (o,f))[1] is not f: | ||||
raise TypeError( | ||||
"%r already has method for object %r" % (func, o) | ||||
) | ||||
return f | ||||
return decorate | ||||
def dispatch(*args, **kw): | ||||
f = _gbo(id(args[0]), _sentinel) | ||||
if f is _sentinel: | ||||
for t in type(args[0]).__mro__: | ||||
f = _gbt(t, _sentinel) | ||||
if f is not _sentinel: | ||||
return f(*args, **kw) | ||||
else: | ||||
return func(*args, **kw) | ||||
else: | ||||
return f[1](*args, **kw) | ||||
try: | ||||
dispatch.__name__ = func.__name__ | ||||
except TypeError: | ||||
pass | ||||
dispatch.__dict__ = func.__dict__.copy() | ||||
dispatch.__doc__ = func.__doc__ | ||||
dispatch.__module__ = func.__module__ | ||||
dispatch.when_type = when_type | ||||
dispatch.when_object = when_object | ||||
dispatch.default = func | ||||
dispatch.has_object = lambda o: id(o) in _by_object | ||||
dispatch.has_type = lambda t: t in _by_type | ||||
return dispatch | ||||
def test_suite(): | ||||
import doctest | ||||
return doctest.DocFileSuite( | ||||
'README.txt', | ||||
optionflags=doctest.ELLIPSIS|doctest.REPORT_ONLY_FIRST_FAILURE, | ||||
) | ||||