Re: [Amforth-devel] words: tuck/under etc

[Ulrich H. <uh...@xl...>]

Hi Bernie, Mike,

> Is the solution now to use *: perform postpone @ postpone execute; *??


yes

In Forth-83 there were two distinct words for user defined
compilation: COMPILE for non-immediate words and [COMPILE] for
immediate words.

However some special Forth systems had immediate words which
are non-immediate in typical systems: for example cmForth
defines @ as an immediate compiler macro.

Thus the use of COMPILE and [COMPILE] was not portable to
those systems.

POSTPONE tries to hide the immediateness
of the compiled word, so POSTPONE @ compiles the
correct code whether or not @ is immediate.

Interesting enough, if you want to emulate POSTPONE
on older systems with COMPILE and [COMPILE] you have
to deal with the immediateness of the compiled word in
order to hide it...

Regards,
		Ulli

Am 15.07.2008 um 23:28 schrieb Bernard Mentink:

> Thanks Michael,
>
> I don't understand German but I get the code, I had found the  
> definition to
> tuck elsewhere, I just wanted to check it was correct.
>
> Also I am still having trouble with the old style forth in the
> definition :*perform compile @ compile execute ;
> *
> Is the solution now to use *: perform postpone @ postpone execute; *??
>
> Cheers,
> Bernie
>
> 2008/7/16 Kalus Michael <mic...@on...>:
>
>> Guten Abend Bernard.
>>
>> Am 15.07.2008 um 03:03 schrieb Bernard Mentink:
>>> .. does anyone
>>> have the definition for "tuck" at hand?
>>
>> : tuck ( w1 w2 – w2 w1 w2 ) \ core-ext "tuck"
>>  swap over ;
>>
>> Beispiel aus gforth:
>>
>> 11 22 .s
>> <2> 11 22  ok
>> tuck .s
>> <3> 22 11 22  ok
>>
>> 33 44 .s
>> <5> 22 11 22 33 44  ok
>> swap over .s
>> <6> 22 11 22 44 33 44  ok
>>
>> Tuck ist nützlich wenn es als code definiert ist, weil die
>> Kkombiantion SWAP OVER doch häufiger vorkommt. Ist aber nicht sooo
>> dringend das zu implementieren, es sei denn du hättest wirklich sehr
>> laufzeitkritischen Code hast.
>>
>> Grüße, Michael
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