def __new__(meta, name, bases, dict):
# @ Metaclass' __new__ serves as a bi-functional slot capable for
# initiating the classes as well as alternating the meta.
# @ Suggestion is putting majority of the class initialization code
# in __init__, as you can directly reference to cls there; saving
# here for anything you want to dynamically added to the meta (such
# as shared variables or lazily GC'd temps).
# @ Any changes here to dict will be visible to the new class and their
# future instances, but won't affect the metaclass. While changes
# directly through meta will be visible to all (unless you override
# it later).
dict['new_elem'] = "effective"
meta.var = "Change made to %s by metaclass' __new__" % str(meta)
meta.count += 1
print "================================================================"
print " Metaclass's __new__ (creates class objects)"
print "----------------------------------------------------------------"
print "Bounded to object: " + str(meta)
print "Bounded object's __dict__: "
pprint(DictType(meta.__dict__), depth = 1)
print "----------------------------------------------------------------"
print "Parameter 'name': " + str(name)
print "Parameter 'bases': " + str(bases)
print "Parameter 'dict': "
pprint(dict, depth = 1)
print "\n"
return super(FactoryMeta, meta).__new__(meta, name, bases, dict)
def __new__(cls, function):
# @ Class' __new__ "creates" the instances.
# @ This won't affect the metaclass. But it does alter the class' member
# as it is bounded to cls.
cls.extra = function
print "================================================================"
print " Class' __new__ (\"creates\" instance objects)"
print "----------------------------------------------------------------"
print "Bounded to object: " + str(cls)
print "Bounded object's __dict__: "
pprint(DictType(cls.__dict__), depth = 1)
print "----------------------------------------------------------------"
print "Parameter 'function': \n" + str(function)
print "\n"
return super(Factory, cls).__new__(cls)
def __init__(self, function, *args, **kwargs):
# @ Class' __init__ initializes the instances.
# @ Changes through self here (normally) won't affect the class or the
# metaclass; they are only visible locally to the instances.
# @ However, here you have another chance to make "static" things
# visible to the instances, "locally".
self.classFactory = self.__class__.classFactory
print "================================================================"
print " Class' __init__ (initiates instance objects)"
print "----------------------------------------------------------------"
print "Bounded to object: " + str(self)
print "Bounded object's __dict__: "
pprint(DictType(self.__dict__), depth = 1)
print "----------------------------------------------------------------"
print "Parameter 'function': \n" + str(function)
print "\n"
return super(Factory, self).__init__(*args, **kwargs)
def __init__(cls, name, bases, dict):
# @ Metaclass' __init__ is the standard slot for class initialization.
# Classes' common variables should mainly goes in here.
# @ Any changes here to dict won't actually affect anything. While
# changes directly through cls will be visible to the created class
# and its future instances. Metaclass remains untouched.
dict['init_elem'] = "defective"
cls.var = "Change made to %s by metaclass' __init__" % str(cls)
print "================================================================"
print " Metaclass's __init__ (initiates class objects)"
print "----------------------------------------------------------------"
print "Bounded to object: " + str(cls)
print "Bounded object's __dict__: "
pprint(DictType(cls.__dict__), depth = 1)
print "----------------------------------------------------------------"
print "Parameter 'name': " + str(name)
print "Parameter 'bases': " + str(bases)
print "Parameter 'dict': "
pprint(dict, depth = 1)
print "\n"
return super(FactoryMeta, cls).__init__(name, bases, dict)
def __call__(cls, *args):
# @ Metaclass' __call__ gets called when a class name is used as a
# callable function to create an instance. It is called before the
# class' __new__.
# @ Instance's initialization code can be put in here, although it
# is bounded to "cls" rather than instance's "self". This provides
# a slot similar to the class' __new__, where cls' members can be
# altered and get copied to the instances.
# @ Any changes here through cls will be visible to the class and its
# instances. Metaclass remains unchanged.
cls.var = "Change made to %s by metaclass' __call__" % str(cls)
# @ "Static" methods defined in the meta which cannot be seen through
# instances by default can be manually assigned with an access point
# here. This is a way to create shared methods between different
# instances of the same metaclass.
cls.metaVar = FactoryMeta.metaVar
print "================================================================"
print " Metaclass's __call__ (initiates instance objects)"
print "----------------------------------------------------------------"
print "Bounded to object: " + str(cls)
print "Bounded object's __dict__: "
pprint(DictType(cls.__dict__), depth = 1)
print "\n"
return super(FactoryMeta, cls).__call__(*args)
