重新定义单词 [英] Word redefinition in Forth

问题描述

在Forth中，如果重新定义单词，那么使用重新定义的单词的另一个单词的预期行为是什么? 例如如果x调用y:

In Forth, in case of re-definition of word, what is the expected behavior of another word that uses the re-defined one? For e.g. if x calls y:

: Y ." Old Y " CR ;
: X 10 0 DO Y LOOP ;
\ ... 
: Y ." New Y " ;

然后在重新定义Y之后，X，Old Y或New Y的输出应该是什么?

then after the re-definition of Y, what should be the output of X, Old Y or New Y ?

推荐答案

简短的答案:X将输出Old Y，另请参见

The short answer: X will output Old Y, see also your example in online test. At the time when Y is defined in the second time, the X is already compiled.

在Forth中，重定义只是遮蔽:新定义的名称遮盖了同一单词列表中的另一个名称，并且被该名称遮盖的定义变得不可访问(无法找到)的情况.

In Forth, redefinition is just shadowing: it is the case when the name of a new definition shadows some another name in the same word list, and the shadowed definition becomes inaccessible (unfindable) by this name.

也Forth使用增量编译和静态名称解析(在编译时间).结果，新的定义不会影响任何以前的定义(和已经编译的代码).

Also Forth uses incremental compilation and static name resolution (that is performed in compile time). As the result, the new definitions don't affect any previous definitions (and already compiled code).

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