Update of /cvsroot/modeling/ProjectModeling/Modeling
In directory sc8-pr-cvs1:/tmp/cvs-serv13130
Added Files:
Tag: brch-0_9pre7-1-PyModel
mems_lib.py
Log Message:
Added
--- NEW FILE: mems_lib.py ---
##
## The following code is taken from the ZODB Programmer's Guide
##
from types import ClassType,TypeType
import __builtin__
# The built-in 'isinstance()' and 'issubclass()' won't work on
# ExtensionClasses, so you have to use the versions supplied here.
# (But those versions work fine on regular instances and classes too,
# so you should *always* use them.)
def issubclass (class1, class2):
"""A version of 'issubclass' that works with extension classes
as well as regular Python classes.
"""
# Both class objects are regular Python classes, so use the
# built-in 'issubclass()'.
if type(class1) is ClassType and type(class2) is ClassType:
return __builtin__.issubclass(class1, class2)
# Both so-called class objects have a '__bases__' attribute: ie.,
# they aren't regular Python classes, but they sure look like them.
# Assume they are extension classes and reimplement what the builtin
# 'issubclass()' does behind the scenes.
elif hasattr(class1, '__bases__') and hasattr(class2, '__bases__'):
# XXX it appears that "ec.__class__ is type(ec)" for an
# extension class 'ec': could we/should we use this as an
# additional check for extension classes?
# Breadth-first traversal of class1's superclass tree. Order
# doesn't matter because we're just looking for a "yes/no"
# answer from the tree; if we were trying to resolve a name,
# order would be important!
stack = [class1]
while stack:
if stack[0] is class2:
return 1
stack.extend(list(stack[0].__bases__))
del stack[0]
else:
return 0
# Not a regular class, not an extension class: blow up for consistency
# with builtin 'issubclass()"
else:
raise TypeError, "arguments must be class or ExtensionClass objects"
# issubclass ()
def isinstance (object, klass):
"""A version of 'isinstance' that works with extension classes
as well as regular Python classes."""
if type(klass) is TypeType:
return __builtin__.isinstance(object, klass)
elif hasattr(object, '__class__'):
return issubclass(object.__class__, klass)
else:
return 0
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