在Smalltalk中新建和初始化的區別？

Question

一個新手問題，new和initialize有什麼區別？

奧斯卡

Answer 1

沒錯。當您發送消息#new時，它不僅創建對象，而且還發送消息#initialize。這可讓您自定義對象的初始化。看：

Behavior >> new 
"Answer a new initialized instance of the receiver (which is a class) with no indexable variables. Fail if the class is indexable." 

^ self basicNew initialize 

然後：

ProtoObject >> initialize 
"Subclasses should redefine this method to perform initializations on instance creation" 

和：

Behaviour >> basicNew 
"Primitive. Answer an instance of the receiver (which is a class) with no 
indexable variables. Fail if the class is indexable. Essential. See Object 
documentation whatIsAPrimitive." 

<primitive: 70> 
self isVariable ifTrue: [^self basicNew: 0 ]. 
"space must be low" 
OutOfMemory signal. 
^ self basicNew "retry if user proceeds" 

所以...＃basicNew是原始的創建對象。通常情況下，你使用#new，如果你不想特殊的東西，你不會實現#initialize，因此#ProtoObject的空實現將被執行。否則，你可以直接發送#basicNew，但你可能不應該這樣做。

乾杯

Answer 2

有了新創建一個新的對象，而在創建新對象時，執行初始化方法，以及初始化對象。

Answer 3

Bavarious是正確的。

Behavior >> new 
     "Answer a new instance of the receiver. If the instance can have indexable variables, it will have 0 indexable variables." 

     "Primitive fails if the class is indexable." 
     <primitive: 70> 
     self isVariable ifTrue: [^self new: 0]. 
     self primitiveFailed 

Object >> initialize 
    "Initialize the object to its default state. This is typically used in a convention that the class implements the #new method to call #initialize automatically. This is not done for all objects in VisualWorks, but the initialize method is provided here so that subclasses can call 'super initialize' and not get an exception." 

    ^self.