Python2.7 以及 Python 3.5的实例方法,类方法,静态方法之间的区别及调用关系

　　今天很好奇Python2.7 和Python 3.5 的实例方法、类方法、静态方法之间的

区别与联系。所以就做了两个小实验来测验一下

Python3.5及以上

类的定义

class Test():
def instanceMethod(self):  # 实例方法，必须传入自身实例（self）作为参数
print("I am the instancemethold,because I have the parmeter self")

@classmethod
def classMethod(cls): # 类方法，传入类实例
print("I am the classMethod,because I have the @ modifier ,and my paramter has cls")

@staticmethod
def staticMethod(): # 静态方法
print("I am the staticMethod,because I have the @ modifier ")

def normalMethod(): # 普通方法
print("I am a noemal method Because I have nothing")

测验结果：

一、实例对各种方法的调用：

t=Test()
t.instanceMethod()
t.classMethod()
t.staticMethod()
t.normalMethod()

# 输出
I am the instancemethold,because I have the parmeter self
I am the classMethod,because I have the "@ modifier" ,and my paramter has cls
I am the staticMethod,because I have the @ modifier
Traceback (most recent call last):
File "D:/Python/test.py", line 22, in <
4000
;module>
t.normalMethod()
TypeError: normalMethod() takes 0 positional arguments but 1 was given

二、类对各种方法的调用：

t=Test()
Test.instanceMethod(t)
Test.classMethod()
Test.staticMethod()
Test.normalMethod()

# 输出
I am the instancemethold,because I have the parmeter self
I am the classMethod,because I have the "@ modifier" ,and my paramter has cls
I am the staticMethod,because I have the @ modifier
I am a normal method Because I have nothing

Python2.7中：

类的定义：

class Test():
def instanceMethod(self):  # 实例方法，必须传入自身实例（self）作为参数
print("I am the instancemethold,because I have the parmeter self")

@classmethod
def classMethod(cls): # 类方法，传入类实例
print("I am the classMethod,because I have the @ modifier ,and my paramter has cls")

@staticmethod
def staticMethod(): # 静态方法
print(" am the staticMethod,because I have the @ modifier ")

def normalMethod(): # 普通方法
print("I am a noemal method Because I have nothing")

一、实例对各种方法的调用：

========================= RESTART: D:\Python\test.py =========================
>>> t=Test()
>>> t.instanceMethod
<bound method Test.instanceMethod of <__main__.Test instance at 0x02BCC738>>
>>> t.instanceMethod()  # 实例可以调用实例方法，self为默认参数，不用传
I am the instancemethold,because I have the parmeter self
>>> t.classMethod
<bound method classobj.classMethod of <class __main__.Test at 0x004FB378>>
>>> t.classMethod()  # 实例可以调用类方法
I am the classMethod,because I have the @ modifier ,and my paramter has cls
>>> t.staticMethod
<function staticMethod at 0x02C09D30>
>>> t.staticMethod() # 实例可以调用静态方法
am the staticMethod,because I have the @ modifier
>>> t.normalMethod
<bound method Test.normalMethod of <__main__.Test instance at 0x02BCC738>>
>>> t.normalMethod() # 实例不可以调用普通方法

Traceback (most recent call last):
File "<pyshell#8>", line 1, in <module>
t.normalMethod()
TypeError: normalMethod() takes no arguments (1 given)
>>>

二、类对各种方法的调用：

========================= RESTART: D:\Python\test.py =========================
>>> Test.instanceMethod()

Traceback (most recent call last):
File "<pyshell#10>", line 1, in <module>
Test.instanceMethod()
TypeError: unbound method instanceMethod() must be called with Test instance as first argument (got nothing instead)
>>> Test.instanceMethod(t) # 类调用实例方法需传入实例对象作为参数
I am the instancemethold,because I have the parmeter self
>>> Test.classMethod() # 类调用类方法
I am the classMethod,because I have the @ modifier ,and my paramter has cls
>>> Test.staticMethod
<function staticMethod at 0x02C09D30>
>>> Test.staticMethod() # 类调用静态方法
am the staticMethod,because I have the @ modifier
>>> Test.normalMethod
<unbound method Test.normalMethod>
>>> Test.normalMethod()  #类不能调用普通方法

Traceback (most recent call last):
File "<pyshell#17>", line 1, in <module>
Test.normalMethod()
TypeError: unbound method normalMethod() must be called with Test instance as first argument (got nothing instead)
>>>

总结 :

　　 以上实验说明，实例可以访问实例方法、类方法、静态方法 ，普通方法不能访问；类可以访问实例方法（必须传入类的实例作为参数）、类方法、静态方法，普通方法不能访问。

　　 实例可以访问实例方法也可以访问类方法，类可以访问类方法也可以访问实例方法，但是类方法在访问实例方法的时候必须传入类的实例作为参数，类可以理解为实例的一种。类本身可以访问函数，但是实例确不可以。

　　但是在Python2.7中类不能调用普通函数，在Python3.5h中类方法可以调用普通函数，具体体现在

Test.normalMethod()的使用当中。