35 lines
867 B
Forth
35 lines
867 B
Forth
## Hooks
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RETRO 11 allowed nearly all definitions to be temporarily replaced by leaving space at the start for compiling in a jump. In the current RETRO I do not do this, though the technique is still useful.
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The next few words add a means of doing this in RETRO 12.
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To allow a word to be overridden, add a call to `hook` as the first word in the definition. This will compile a jump to the actual definition start.
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~~~
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:hook (-) #1793 , here n:inc , ; immediate
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~~~
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`set-hook` takes a pointer to the new word or quote and a pointer to the hook to replace. It alters the jump target.
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~~~
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:set-hook (aa-) n:inc store ;
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~~~
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The final word, `unhook`, resets the jump target to the original one.
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~~~
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:unhook (a-) n:inc dup n:inc swap store ;
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~~~
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## Test
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```
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:test hook #1 #2 + n:put ;
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test nl
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[ 'hello s:put ] &test set-hook
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test nl
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&test unhook
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test nl
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```
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