如何使用复合规范模式实现 isGeneralizationOf ？

发布于 2024-10-16 18:47:36 字数 788 浏览 7 评论 0原文

我正在尝试按照 Fowler 和 Evans 的规范文档来实现复合规范模式。

乍一看，我认为 isGeneralizationOf 的实现对于合取和析取会有所不同。

特别是，我认为合取的逻辑是

(1) 令specX 为specA 和specB 的合取。那么，只有当specA和specB都是specC的泛化时，specX才是specC的泛化。

并且我认为析取的逻辑将是

(2)令specY为specA和specB的析取。那么，如果specA或specB是specC的泛化，则specY是specC的泛化。

但是，在文档的第16页上，他们展示了这个方法：

CompositeSpecification >> isGeneralizationOf: aSpecification
"True if each component is subsumed. False if any component is not subsumed."
^ (self components contains:
        [:each |(each isGeneralizationOf: aSpecification) not ]) not

我在（1）和（2）中的推理正确吗？如果是错的，那是为什么呢？如果它是正确的，那么为什么作者定义一个由合取和析取规范继承的单一方法？他们来这里的目的是什么？

原文

I am trying to implement the composite specification pattern, as per the Specifications Document by Fowler and Evans.

At first impression, I thought the implementation of isGeneralizationOf would be different for conjunction and disjunction.

In particular, I thought the logic for conjunction would be

(1) Let specX be the conjunction of specA and specB. Then, specX is a generalization of specC only if both specA and specB are a generalization of specC.

And I thought the logic for disjunction would be

(2) Let specY be the disjunction of specA and specB. Then, specY is a generalization of specC if either specA or specB is a generalization of specC.

However, on page 16 of the document , they show this method:

CompositeSpecification >> isGeneralizationOf: aSpecification
"True if each component is subsumed. False if any component is not subsumed."
^ (self components contains:
        [:each |(each isGeneralizationOf: aSpecification) not ]) not

Is my reasoning in (1) and (2) correct? If it's wrong, why is that? If it's correct, then why did the authors define a single method to be inherited by both conjunction and disjunction specifications? What is their intent here?

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只有影子陪我不离不弃 2024-10-23 18:47:36

示例：

The following models: the spec "a AND b" is specialization of "a OR b"

({a,b} isSpecializationOf: {a}) & ({a,b} isSpecializationOf: {b})
-> true

This following models: the spec "a OR b" is specialization of "a AND b"

({a} isSpecializationOf: {a,b}) | ({b} isSpecializationOf: {a,b})
-> false

如果您首先定义对象 a 和 b，则可以在 Squeak 中获得如此好的语法，因为 {} 是动态数组文字的特殊语法（在 Array 类中定义 isSpecializationOf:）。

Examples:

The following models: the spec "a AND b" is specialization of "a OR b"

({a,b} isSpecializationOf: {a}) & ({a,b} isSpecializationOf: {b})
-> true

This following models: the spec "a OR b" is specialization of "a AND b"

({a} isSpecializationOf: {a,b}) | ({b} isSpecializationOf: {a,b})
-> false

You can get the syntax this nice in Squeak if you first define the objects a and b, since {} is a special syntax for dynamic array literals (define isSpecializationOf: in class Array).

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带刺的爱情 2024-10-23 18:47:36

CompositeSpecification >> isGeneralizationOf: aSpecification
^aSpecification isSpecializationOf: self

CompositeSpecification >> isSpecializationOf: aSpecification
^self components includesAllOf: aSpecification

#includesAllOf：在类 Collection 中定义

CompositeSpecification >> isGeneralizationOf: aSpecification
^aSpecification isSpecializationOf: self

CompositeSpecification >> isSpecializationOf: aSpecification
^self components includesAllOf: aSpecification

#includesAllOf: is defined in the class Collection

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