classonlymethod和classmethod区别
如果要使用classonlymethod ,则需要先定义好一个classonlymethod 类。
首先我们需要明白无论是classonlymethod还是classmethod，本质都是一个类，而classonlymethod继承了classmethod。
classonlymethodz作用:只能被类调用，不能被实例对象调用。
class classonlymethod(classmethod): # 继承classmethod
def __get__(self, instance, cls=None): #
if instance is not None:
raise AttributeError("This method is available only on the class, not on instances.")
return super(classonlymethod, self).__get__(instance, cls)
示例2
from django.utils.decorators import classonlymethod
class Foo:
def __init__(self, name, a = None):
self.name = name
@classonlymethod
def as_view(cls, actions=None, **initkwargs):
"""
Because of the way class based views create a closure around the
instantiated view, we need to totally reimplement `.as_view`,
and slightly modify the view function that is created and returned.
"""
# The name and description initkwargs may be explicitly overridden for
# certain route confiugurations. eg, names of extra actions.
cls.name = None
cls.description = None
page = None
# The suffix initkwarg is reserved for displaying the viewset type.
# This initkwarg should have no effect if the name is provided.
# eg. 'List' or 'Instance'.
cls.suffix = None
# The detail initkwarg is reserved for introspecting the viewset type.
cls.detail = None
# Setting a basename allows a view to reverse its action urls. This
# value is provided by the router through the initkwargs.
cls.basename = None
# actions must not be empty
if not actions:
raise TypeError("The `actions` argument must be provided when "
"calling `.as_view()` on a ViewSet. For example "
"`.as_view({'get': 'list'})`")
def tell(self): # 绑定到对象
print('名字是%s'%self.name)
@classonlymethod
def tell2(cls, page=None): # 绑定到对象
print('@classonlymethod名字是%s'%cls.tell)
if page is not None:
print(page,'page你好啊')
@classmethod # 绑定到类
def func(cls):
print(cls,'这是classmethod')
@staticmethod # 非绑定方法,静态方法
def func1(x,y):
print(x+y)
f = Foo('egon')
print(f,'对象f')
def func3():print('这是函数func3')
print(Foo.func,'函数func')
Foo.func()
print('-----------1-----------')
Foo.tell2()
print(Foo.tell2.__module__)
Foo.tell2(123)
print('---------2-------------')
# f.tell2()
Foo.as_view(actions='get')
f.as_view(actions='get') #
print(Foo.as_view.__module__)
输出:
Traceback (most recent call last):
File "D:/python3.64/sss/python_note/面向对象/21_绑定方法与非绑定方法介绍.py", line 72, in <module>
f.as_view(actions='get') #
File "D:\PythonVenv\drf_venv\lib\site-packages\django\utils\decorators.py", line 11, in __get__
raise AttributeError("This method is available only on the class, not on instances.")
AttributeError: This method is available only on the class, not on instances.
<__main__.Foo object at 0x00000228236ED3C8> 对象f
<bound method Foo.func of <class '__main__.Foo'>> 函数func
<class '__main__.Foo'> 这是classmethod
-----------1-----------
@classonlymethod名字是<function Foo.tell at 0x000002282392C8C8>
__main__
@classonlymethod名字是<function Foo.tell at 0x000002282392C8C8>
123 page你好啊
---------2-------------
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