对python中class与变量的使用方法详解

　　python中的变量定义是很灵活的，很容易搞混淆，特别是对于class的变量的定义，如何定义使用类里的变量是我们维护代码和保证代码稳定性的关键。 global_variable_1 = ＂global_variable＂   class MyClass():   class_var_1 = ＂class_val_1＂ # define class variable here   def __init__(self, param):     self.object_var_1 = param # define object variable here     self.object_var_2 = ＂object_val_2＂ # define object variable here     self.object_func3()     def object_func1(self, param):     local_var_1 = param # define lcoal variable here     local_var_2 = ＂local_val_2＂ # define local variable here     self.internal_var_1 = ＂internal_val_1＂ # define internal variable here     print(local_var_1) # we can use local variable of current here     print(local_var_2) # we can use local variable of current here     print(MyClass.class_var_1) # we can use class variable here, but you have using class name ass prefix     print(self.class_var_1) # we can use class variable as object variable here     print(self.object_var_1) # we can use object variable here     print(self.object_var_2) # we can use object variable here     print(self.internal_var_1) # we can use internal variable here     #print(local_var_3) # we can＂t use local variable in another function     print(global_variable_1) # we can use global variable here     def object_func2(self, param=＂func_val_1＂):     local_var_3 = param # define local variable here     print(local_var_3) # we can use lcoal variable here     print(self.internal_var_1) # we can use internal variable defined in class_func1, but you have to call class_func1 first     print(MyClass.class_var_1) # we can use class variable here, but you have using class name ass prefix     print(self.class_var_1) # we can class variable here     print(self.object_var_1) # we can use object variable here     print(self.object_var_2) # we can use object variable here     print(global_variable_1) # we can use global variable here       def object_func3(self, param=＂func_val_1＂):     self.object_var_3 = param # because this function called in construction function, so this is defined as object variable, not internal variable     self.object_var_4 = ＂object_val_4＂ # because this function called in construction function, so this is defined as object variable, not internal variable     print(global_variable_1) # we can use global variable here      # define class function   def class_func4():     print(MyClass.class_var_1)     print(global_variable_1) # we can use global variable here   if __name__ == ＂__main__＂:   myObject = MyClass(＂object_val_1＂)   print(MyClass.class_var_1) # we can use class variable directly here   #print(MyClass.object_var_1) # we can＂t use object variable here   print(myObject.object_var_1) # we can use object variable here   print(myObject.object_var_2) # we can use object variable here   print(myObject.object_var_3) # we can use object variable here   print(myObject.object_var_4) # we can use object variable here   #print(myObject.internal_var_1) # we can＂t use internal variable as object variable here   MyClass.class_func4() # we can use class function here   #MyClass.object_func2(myObject, ＂local_var_3＂) # internal variable can＂t be used in this function   myObject.object_func1(＂local_var_1＂) # call first function   myObject.object_func2(＂local_var_3＂) # call second function   print(global_variable_1) # we can use global variable here
　　枚举了各种情况，没有办法全部枚举，但大部分情况应该都已经包含了。
　　1. 类变量：能够通过类名或者object的self来访问到，在类的内部和外部均可达，比如class_var_1
　　2. 对象变量：可以通过对象的self来使用的变量，通过constructor一路走向去的的self初次被赋值的变量都会成为对象变量，比如object_var_1, object_var_2, object_var_3, object_var_4
　　3. 内部变量：可以在函数中定义，并加上self前缀，在初次调用过定义的函数后，就可以在后面的对象的函数中被使用，比如internal_var_1
　　4. 局部变量：在函数内部定义，并使用的变量，在使用完之后就会被回收对类及object不可见
　　5. 全局变量：定义在类或者函数外部，作用域在变量被定义之后的任意代码段，比如：global_var_1