Python – __init__ & __call__

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測試環境為 CentOS 8 x86_64 (虛擬機)

下面來看一下 __init__ & __call__ 的使用時機.

• object.__init__(self[, …]) – https://docs.python.org/3/reference/datamodel.html#object.__init__
  Called after the instance has been created (by __new__())
• object.__call__(self[, args…]) – https://docs.python.org/3/reference/datamodel.html#object.__call__
  Called when the instance is “called” as a function.

參考文章 – https://vimsky.com/zh-tw/examples/usage/__call__-in-python.html

• 範例 :

  [root@localhost ~]# vi call.py class Product:     def __init__(self):         print("Instance Created")         def __call__(self, a, b):         print(a * b)   ans = Product()   ans(10, 20)

  執行結果

  [root@localhost ~]# python3 call.py Instance Created 200

  說明:
  在建立 Instance 時就會去呼叫 __init__ (初始化函式).

  ans = Product()

  執行結果

  Instance Created

  當 Instance 作為函數時使用就會去呼叫 __call__ 涵式.

  ans(10, 20)

  執行結果

  200