python中的type函数-python的type函数

对于type，经常会用到的是判断类型，但是判断类型更推荐的一种方式是使用isinstance();但是很少会用到type的另外一个功能，生成一个新的类型，看官方解释：

class type(name, bases, dict)

With three arguments, return a new type object. This is essentially a dynamic form of the class statement. The name string is the class name and becomes the name attribute; the bases tuple itemizes the base classes and becomes the bases attribute; and the dict dictionary is the namespace containing definitions for class body and becomes the dict attribute. For example, the following two statements create identical type objects:

>>> class X(object):

... a = 1

...

>>> X = type("X", (object,), dict(a=1))

这样就可以产生一个新的类型X。

再举个demo：

django框架中的BaseManager

@classmethod

def from_queryset(cls, queryset_class, class_name=None):

if class_name is None:

class_name = "%sFrom%s" % (cls.__name__, queryset_class.__name__)

class_dict = {

"_queryset_class": queryset_class,

}

class_dict.update(cls._get_queryset_methods(queryset_class))

return type(class_name, (cls,), class_dict)

over...