python中classmethod和Django中classonlymethod区别

classmethod可以被一个实例调用, 但是classonlymethod不能,它只能被类调用.

class classonlymethod(classmethod):
    def __get__(self, instance, owner):
        if instance is not None:
            raise AttributeError('This method is available only on the view class .')
        return super(classonlymethod, self).__get__(instance, owner)

The difference is that a classmethod can be an instance, having the same effect as calling it on the class, but the classonlymethod can only be called on the class.

class Kls(object):
    no_inst = 0
    def __init__(self):
        Kls.no_inst = Kls.no_inst + 1
    @classmethod
    def get_no_of_instance(cls_obj):
        return cls_obj.no_inst
ik1 = Kls()
ik2 = Kls()
print ik1.get_no_of_instance()
print Kls.get_no_of_instance()