smalltalk单例模式:如何初始化实例变量? [英] smalltalk singleton pattern: how do I initialize the instance variables?

问题描述

我在获取单例模式以在smalltalk中初始化实例变量时遇到麻烦. (这是链接到另一个实现进行澄清)

I'm having trouble in getting the singleton pattern to initialize a instance variable in smalltalk. (here is a link to another implementation for clarification)

这就是我所拥有的:

new

^UniqueInstance ifNil: [UniqueInstance := self basicNew.
                        UniqueInstance: instanceVar := Object new. ].

最后一行(UniqueInstance:instanceVar:= Object new.)不起作用，但这基本上是我需要做的:将instanceVar实例化为Object，然后将UniqueInstance返回给调用者.

that last line (UniqueInstance: instanceVar := Object new.) doesn't work, but that's basically what I need to do: instantiate instanceVar as an Object before returning UniqueInstance back to the caller.

请注意，此新"方法用作类实例，并且库是UniqueIsntance(所需类的实例)的实例变量.

Notice that this 'new' method is used as a classinstantiation, and that libraries is a instance variable of UniqueIsntance (the isntance of the wanted class).

有人能指出我正确的方向吗?

Can anyone point me in the right direction?

推荐答案

尝试更简单:

YourClass class>>singleton

       UniqueInstance ifNil: [UniqueInstance := self basicNew initialize].
       ^UniqueInstance

然后在类的实例端实现适当的#initialize方法，例如:

then on instance side of your class implement an appropriate #initialize method, for example:

YourClass>>initialize

          someInstvar := someInitalValue.
         ^self

更新:访问单例的类方法的名称各不相同，可以是#default，#current或#singleton.我以后主要使用.

Update:: Name of the class method accessing the singleton varies, it can be #default, #current, or #singleton. I mostly use later.

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