class _ClassMethod:
# Helper class: instances represent methods bound to a class
def __init__(self, klass, func):
self.func = func
# oops: circular reference!
self.klass = klass
def __call__(self, *args, **kw):
# return result of function call
return self.func(self.klass, *args, **kw)
import ExtensionClass
class Class(ExtensionClass.Base):
def __class_init__(self):
# automagically convert methods to class methods
#
# ExtensionClass.Base calls this _class_ method after the _class_
# has been created!
for mth in self.__class_methods__:
self.__dict__[mth.func_name] = _ClassMethod(self, mth)
def class_method(self, *args, **kw):
# A _class method_ creating an returning new a new instance
# the 'self' argument is actual class itself
print "class_method called with", self, args, kw
return self()
def class_method_2(self, *args, **kw):
# Class methods may return anything they like
print "class_method_2 called with", self, args, kw
return None
def instance_method(self, *args, **kw):
# instance methods behave normally
print "instance_method called with", self, args, kw
# List the methods which should be automagically be converted
# into class methods
__class_methods__ = class_method, class_method_2
class Subclass(Class):
def class_method_2(self):
# override a class method in a subclass
print "Hi from", self
####################################################################
c = Class()
# demonstrate calling class methods
print Class.class_method()
print Class.class_method(1, 2, 3, a=10, b=20, c=30)
print Subclass.class_method()
print Class.class_method_2()
print Subclass.class_method_2()
# demonstrate calling instance methods
c.instance_method()
try:
Class.instance_method()
except Exception, detail:
print "Called instance method off the class:\n\t", detail
# calling class methods off an instance also works...
print c.class_method()
