快捷導(dǎo)航

對(duì)python 中class與變量的使用方法詳解

更新時(shí)間：2019年06月26日 09:56:40 作者：lawenliu

今天小編就為大家分享一篇對(duì)python 中class與變量的使用方法詳解，具有很好的參考價(jià)值，希望對(duì)大家有所幫助。一起跟隨小編過來看看吧

python中的變量定義是很靈活的，很容易搞混淆，特別是對(duì)于class的變量的定義，如何定義使用類里的變量是我們維護(hù)代碼和保證代碼穩(wěn)定性的關(guān)鍵。

#!/usr/bin/python
#encoding:utf-8
 
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

簡(jiǎn)單的寫了個(gè)測(cè)試小程序，枚舉了各種情況，沒有辦法全部枚舉，但大部分情況應(yīng)該都已經(jīng)包含了。

1. 類變量：能夠通過類名或者object的self來訪問到，在類的內(nèi)部和外部均可達(dá)，比如class_var_1

2. 對(duì)象變量：可以通過對(duì)象的self來使用的變量，通過constructor一路走向去的的self初次被賦值的變量都會(huì)成為對(duì)象變量，比如object_var_1, object_var_2, object_var_3, object_var_4

3. 內(nèi)部變量：可以在函數(shù)中定義，并加上self前綴，在初次調(diào)用過定義的函數(shù)后，就可以在后面的對(duì)象的函數(shù)中被使用，比如internal_var_1

4. 局部變量：在函數(shù)內(nèi)部定義，并使用的變量，在使用完之后就會(huì)被回收對(duì)類及object不可見

5. 全局變量：定義在類或者函數(shù)外部，作用域在變量被定義之后的任意代碼段，比如：global_var_1

以上是基于我自己的測(cè)試得到的結(jié)論，如果有不對(duì)的地方，可以幫忙指正。

這篇對(duì)python 中class與變量的使用方法詳解就是小編分享給大家的全部?jī)?nèi)容了，希望能給大家一個(gè)參考，也希望大家多多支持腳本之家。

您可能感興趣的文章: