Smalltalk 语言 享元模式状态 区分内部状态与外部状态

阿木博主一句话概括：Smalltalk^【1】 语言中的享元模式^【2】：内部状态^【3】与外部状态^【4】的区分与应用

阿木博主为你简单介绍：
享元模式是一种结构型设计模式^【5】，用于减少对象的数量，提高性能。在Smalltalk语言中，享元模式通过区分内部状态和外部状态来实现对象的共享。本文将围绕这一主题，探讨Smalltalk语言中享元模式的应用，分析内部状态与外部状态的差异，并提供相关代码示例。

一、
享元模式是一种常用的设计模式，尤其在性能要求^【6】较高的系统中，如游戏、图形界面等。Smalltalk语言作为一种面向对象的语言，非常适合实现享元模式。本文将介绍Smalltalk语言中的享元模式，并分析内部状态与外部状态的区别。

二、内部状态与外部状态
1. 内部状态
内部状态是指对象内部不会改变的数据，如颜色、大小等。这些状态在对象创建后不会发生变化，因此可以被共享。在Smalltalk中，内部状态通常通过实例变量^【7】来表示。

2. 外部状态
外部状态是指对象在运行过程中会发生变化的数据，如位置、名称等。这些状态在对象创建后可能会改变，因此不能被共享。在Smalltalk中，外部状态通常通过方法参数^【8】或临时变量^【9】来传递。

三、Smalltalk语言中的享元模式实现
以下是一个Smalltalk语言中享元模式的简单实现，用于演示如何区分内部状态和外部状态。

```smalltalk
| color size shape<sup>【10】</sup> |

Class <>
classVariable: 'color' put: 'red'.
classVariable: 'size' put: 10.
classVariable: 'shape' put: 'circle'.

classMethod: 'createWithColor:' [
| color |
color := self classVariable: 'color'.
self new color: color size: self classVariable: 'size' shape: self classVariable: 'shape'.
].

instanceMethod<sup>【11】</sup>: 'draw' [
"Draw the shape with the given color and size."
| color size |
color := self color.
size := self size.
"Drawing code here..."
System out <>.
].

instanceMethod: 'setColor<sup>【12】</sup>:' [
| color |
color := self argumentsAt: 1.
self classVariable: 'color' put: color.
].

instanceMethod: 'setSize<sup>【13】</sup>:' [
| size |
size := self argumentsAt: 1.
self classVariable: 'size' put: size.
].

instanceMethod: 'setShape<sup>【14】</sup>:' [
| shape |
shape := self argumentsAt: 1.
self classVariable: 'shape' put: shape.
].

instanceMethod: 'color' [
self classVariable: 'color'.
].

instanceMethod: 'size' [
self classVariable: 'size'.
].

instanceMethod: 'shape' [
self classVariable: 'shape'.
].

instanceMethod: 'toString' [
"Return a string representation of the shape."
| color size shape |
color := self color.
size := self size.
shape := self shape.
(color size shape) asString.
].

instanceMethod: 'initialize<sup>【15】</sup>' [
"Initialize the shape with default values."
self setColor: 'red'.
self setSize: 10.
self setShape: 'circle'.
].

instanceMethod: 'initialize' [
"Initialize the shape with default values."
self setColor: 'red'.
self setSize: 10.
self setShape: 'circle'.
].

instanceMethod: 'initialize' [
"Initialize the shape with default values."
self setColor: 'red'.
self setSize: 10.
self setShape: 'circle'.
].

instanceMethod: 'initialize' [
"Initialize the shape with default values."
self setColor: 'red'.
self setSize: 10.
self setShape: 'circle'.
].

instanceMethod: 'initialize' [
"Initialize the shape with default values."
self setColor: 'red'.
self setSize: 10.
self setShape: 'circle'.
].

instanceMethod: 'initialize' [
"Initialize the shape with default values."
self setColor: 'red'.
self setSize: 10.
self setShape: 'circle'.
].

instanceMethod: 'initialize' [
"Initialize the shape with default values."
self setColor: 'red'.
self setSize: 10.
self setShape: 'circle'.
].

instanceMethod: 'initialize' [
"Initialize the shape with default values."
self setColor: 'red'.
self setSize: 10.
self setShape: 'circle'.
].

instanceMethod: 'initialize' [
"Initialize the shape with default values."
self setColor: 'red'.
self setSize: 10.
self setShape: 'circle'.
].

instanceMethod: 'initialize' [
"Initialize the shape with default values."
self setColor: 'red'.
self setSize: 10.
self setShape: 'circle'.
].

instanceMethod: 'initialize' [
"Initialize the shape with default values."
self setColor: 'red'.
self setSize: 10.
self setShape: 'circle'.
].

instanceMethod: 'initialize' [
"Initialize the shape with default values."
self setColor: 'red'.
self setSize: 10.
self setShape: 'circle'.
].

instanceMethod: 'initialize' [
"Initialize the shape with default values."
self setColor: 'red'.
self setSize: 10.
self setShape: 'circle'.
].

instanceMethod: 'initialize' [
"Initialize the shape with default values."
self setColor: 'red'.
self setSize: 10.
self setShape: 'circle'.
].

instanceMethod: 'initialize' [
"Initialize the shape with default values."
self setColor: 'red'.
self setSize: 10.
self setShape: 'circle'.
].

instanceMethod: 'initialize' [
"Initialize the shape with default values."
self setColor: 'red'.
self setSize: 10.
self setShape: 'circle'.
].

instanceMethod: 'initialize' [
"Initialize the shape with default values."
self setColor: 'red'.
self setSize: 10.
self setShape: 'circle'.
].

instanceMethod: 'initialize' [
"Initialize the shape with default values."
self setColor: 'red'.
self setSize: 10.
self setShape: 'circle'.
].

instanceMethod: 'initialize' [
"Initialize the shape with default values."
self setColor: 'red'.
self setSize: 10.
self setShape: 'circle'.
].

instanceMethod: 'initialize' [
"Initialize the shape with default values."
self setColor: 'red'.
self setSize: 10.
self setShape: 'circle'.
].

instanceMethod: 'initialize' [
"Initialize the shape with default values."
self setColor: 'red'.
self setSize: 10.
self setShape: 'circle'.
].

instanceMethod: 'initialize' [
"Initialize the shape with default values."
self setColor: 'red'.
self setSize: 10.
self setShape: 'circle'.
].

instanceMethod: 'initialize' [
"Initialize the shape with default values."
self setColor: 'red'.
self setSize: 10.
self setShape: 'circle'.
].

instanceMethod: 'initialize' [
"Initialize the shape with default values."
self setColor: 'red'.
self setSize: 10.
self setShape: 'circle'.
].

instanceMethod: 'initialize' [
"Initialize the shape with default values."
self setColor: 'red'.
self setSize: 10.
self setShape: 'circle'.
].

instanceMethod: 'initialize' [
"Initialize the shape with default values."
self setColor: 'red'.
self setSize: 10.
self setShape: 'circle'.
].

instanceMethod: 'initialize' [
"Initialize the shape with default values."
self setColor: 'red'.
self setSize: 10.
self setShape: 'circle'.
].

instanceMethod: 'initialize' [
"Initialize the shape with default values."
self setColor: 'red'.
self setSize: 10.
self setShape: 'circle'.
].

instanceMethod: 'initialize' [
"Initialize the shape with default values."
self setColor: 'red'.
self setSize: 10.
self setShape: 'circle'.
].

instanceMethod: 'initialize' [
"Initialize the shape with default values."
self setColor: 'red'.
self setSize: 10.
self setShape: 'circle'.
].

instanceMethod: 'initialize' [
"Initialize the shape with default values."
self setColor: 'red'.
self setSize: 10.
self setShape: 'circle'.
].

instanceMethod: 'initialize' [
"Initialize the shape with default values."
self setColor: 'red'.
self setSize: 10.
self setShape: 'circle'.
].

instanceMethod: 'initialize' [
"Initialize the shape with default values."
self setColor: 'red'.
self setSize: 10.
self setShape: 'circle'.
].

instanceMethod: 'initialize' [
"Initialize the shape with default values."
self setColor: 'red'.
self setSize: 10.
self setShape: 'circle'.
].

instanceMethod: 'initialize' [
"Initialize the shape with default values."
self setColor: 'red'.
self setSize: 10.
self setShape: 'circle'.
].

instanceMethod: 'initialize' [
"Initialize the shape with default values."
self setColor: 'red'.
self setSize: 10.
self setShape: 'circle'.
].

instanceMethod: 'initialize' [
"Initialize the shape with default values."
self setColor: 'red'.
self setSize: 10.
self setShape: 'circle'.
].

instanceMethod: 'initialize' [
"Initialize the shape with default values."
self setColor: 'red'.
self setSize: 10.
self setShape: 'circle'.
].

instanceMethod: 'initialize' [
"Initialize the shape with default values."
self setColor: 'red'.
self setSize: 10.
self setShape: 'circle'.
].

instanceMethod: 'initialize' [
"Initialize the shape with default values."
self setColor: 'red'.
self setSize: 10.
self setShape: 'circle'.
].

instanceMethod: 'initialize' [
"Initialize the shape with default values."
self setColor: 'red'.
self setSize: 10.
self setShape: 'circle'.
].

instanceMethod: 'initialize' [
"Initialize the shape with default values."
self setColor: 'red'.
self setSize: 10.
self setShape: 'circle'.
].

instanceMethod: 'initialize' [
"Initialize the shape with default values."
self setColor: 'red'.
self setSize: 10.
self setShape: 'circle'.
].

instanceMethod: 'initialize' [
"Initialize the shape with default values."
self setColor: 'red'.
self setSize: 10.
self setShape: 'circle'.
].

instanceMethod: 'initialize' [
"Initialize the shape with default values."
self setColor: 'red'.
self setSize: 10.
self setShape: 'circle'.
].

instanceMethod: 'initialize' [
"Initialize the shape with default values."
self setColor: 'red'.
self setSize: 10.
self setShape: 'circle'.
].

instanceMethod: 'initialize' [
"Initialize the shape with default values."
self setColor: 'red'.
self setSize: 10.
self setShape: 'circle'.
].

instanceMethod: 'initialize' [
"Initialize the shape with default values."
self setColor: 'red'.
self setSize: 10.
self setShape: 'circle'.
].

instanceMethod: 'initialize' [
"Initialize the shape with default values."
self setColor: 'red'.
self setSize: 10.
self setShape: 'circle'.
].

instanceMethod: 'initialize' [
"Initialize the shape with default values."
self setColor: 'red'.
self setSize: 10.
self setShape: 'circle'.
].

instanceMethod: 'initialize' [
"Initialize the shape with default values."
self setColor: 'red'.
self setSize: 10.
self setShape: 'circle'.
].

instanceMethod: 'initialize' [
"Initialize the shape with default values."
self setColor: 'red'.
self setSize: 10.
self setShape: 'circle'.
].

instanceMethod: 'initialize' [
"Initialize the shape with default values."
self setColor: 'red'.
self setSize: 10.
self setShape: 'circle'.
].

instanceMethod: 'initialize' [
"Initialize the shape with default values."
self setColor: 'red'.
self setSize: 10.
self setShape: 'circle'.
].

instanceMethod: 'initialize' [
"Initialize the shape with default values."
self setColor: 'red'.
self setSize: 10.
self setShape: 'circle'.
].

instanceMethod: 'initialize' [
"Initialize the shape with default values."
self setColor: 'red'.
self setSize: 10.
self setShape: 'circle'.
].

instanceMethod: 'initialize' [
"Initialize the shape with default values."
self setColor: 'red'.
self setSize: 10.
self setShape: 'circle'.
].

instanceMethod: 'initialize' [
"Initialize the shape with default values."
self setColor: 'red'.
self setSize: 10.
self setShape: 'circle'.
].

instanceMethod: 'initialize' [
"Initialize the shape with default values."
self setColor: 'red'.
self setSize: 10.
self setShape: 'circle'.
].

instanceMethod: 'initialize' [
"Initialize the shape with default values."
self setColor: 'red'.
self setSize: 10.
self setShape: 'circle'.
].

instanceMethod: 'initialize' [
"Initialize the shape with default values."
self setColor: 'red'.
self setSize: 10.
self setShape: 'circle'.
].

instanceMethod: 'initialize' [
"Initialize the shape with default values."
self setColor: 'red'.
self setSize: 10.
self setShape: 'circle'.
].

instanceMethod: 'initialize' [
"Initialize the shape with default values."
self setColor: 'red'.
self setSize: 10.
self setShape: 'circle'.
].

instanceMethod: 'initialize' [
"Initialize the shape with default values."
self setColor: 'red'.
self setSize: 10.
self setShape: 'circle'.
].

instanceMethod: 'initialize' [
"Initialize the shape with default values."
self setColor: 'red'.
self setSize: 10.
self setShape: 'circle'.
].

instanceMethod: 'initialize' [
"Initialize the shape with default values."
self setColor: 'red'.
self setSize: 10.
self setShape: 'circle'.
].

instanceMethod: 'initialize' [
"Initialize the shape with default values."
self setColor: 'red'.
self setSize: 10.
self setShape: 'circle'.
].

instanceMethod: 'initialize' [
"Initialize the shape with default values."
self setColor: 'red'.
self setSize: 10.
self setShape: 'circle'.
].

instanceMethod: 'initialize' [
"Initialize the shape with default values."
self setColor: 'red'.
self setSize: 10.
self setShape: 'circle'.
].

instanceMethod: 'initialize' [
"Initialize the shape with default values."
self setColor: 'red'.
self setSize: 10.
self setShape: 'circle'.
].

instanceMethod: 'initialize' [
"Initialize the shape with default values."
self setColor: 'red'.
self setSize: 10.
self setShape: 'circle'.
].

instanceMethod: 'initialize' [
"Initialize the shape with default values."
self setColor: 'red'.
self setSize: 10.
self setShape: 'circle'.
].

instanceMethod: 'initialize' [
"Initialize the shape with default values."
self setColor: 'red'.
self setSize: 10.
self setShape: 'circle'.
].

instanceMethod: 'initialize' [
"Initialize the shape with default values."
self setColor: 'red'.
self setSize: 10.
self setShape: 'circle'.
].

instanceMethod: 'initialize' [
"Initialize the shape with default values."
self setColor: 'red'.
self setSize: 10.
self setShape: 'circle'.
].

instanceMethod: 'initialize' [
"Initialize the shape with default values."
self setColor: 'red'.
self setSize: 10.
self setShape: 'circle'.
].

instanceMethod: 'initialize' [
"Initialize the shape with default values."
self setColor: 'red'.
self setSize: 10.
self setShape: 'circle'.
].

instanceMethod: 'initialize' [
"Initialize the shape with default values."
self setColor: 'red'.
self setSize: 10.
self setShape: 'circle'.
].

instanceMethod: 'initialize' [
"Initialize the shape with default values."
self setColor: 'red'.
self setSize: 10.
self setShape: 'circle'.
].

instanceMethod: 'initialize' [