|
|
__all__ = ["generic"]
|
|
|
|
|
|
from types import ClassType, InstanceType
|
|
|
classtypes = type, ClassType
|
|
|
|
|
|
# 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__)
|
|
|
|
|
|
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,
|
|
|
)
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
