Re: POSTPONE behaviour

From	Gerry Jackson <gerry@jackson9000.fsnet.co.uk>
Newsgroups	comp.lang.forth
Subject	Re: POSTPONE behaviour
Date	2015-11-25 08:03 +0000
Organization	A noiseless patient Spider
Message-ID	<n33pra$3bn$1@dont-email.me> (permalink)
References	(1 earlier) <b4792de6-8408-4e0c-8d9d-ddc9558500ef@googlegroups.com> <7f06c60a-bc63-4aa3-adfc-877972fa9120@googlegroups.com> <98a20b8e-3531-4d97-9fbb-f16216edca0d@googlegroups.com> <n33ofa$u7g$1@dont-email.me> <afdb9bd1-acb0-4b66-b63a-ae766e121665@googlegroups.com>

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On 25/11/2015 07:48, Aliaksei Chapyzhenka wrote:
> Looks like not much to read, (2 lines) ;)

The important bit is:

"...  Append the compilation semantics of name to the current 
definition. ..."

It doesn't distinguish between immediate and non-immediate words.

So if you have

: foo  postpone drop ; immediate
: bar foo ;

When BAR is being compiled FOO is executed because it is immediate and 
it compiles DROP into BAR because BAR is the "current definition".

>
> https://cloud.githubusercontent.com/assets/511872/11388254/092617c4-92e9-11e5-9bfb-9e0c5433f12a.png
>
> On Tuesday, November 24, 2015 at 11:39:37 PM UTC-8, Gerry wrote:
>> On 25/11/2015 06:54, Raimond Dragomir wrote:
>>>> But failing in this case:
>>>> T{ : GT1 123 ; -> }T
>>>> T{ : GT4 POSTPONE GT1 ; IMMEDIATE -> }T
>>>> T{ : GT5 GT4 ; -> }T
>>>> T{ GT5 -> 123 }T
>>>
>>> Well, think about it: GT4 is immediate. It is executed directly when you
>>> define GT5. When executed it will call GT1 which leaves 123 on the data stack.
>>>
>>> So you already have 123 on the stack after GT5 definition.
>>> Also, GT5 body is just a nop, because you compiled nothing (GT4 just
>>> executed at compile time).
>>> So when you lastly execute GT5 it will leave nothing (but you expect 123)
>>>
>>> Hope it helps
>>>
>> No, you're wrong. If you try it in GForth
>>
>> : GT1 123 ;  ok
>> : GT4 POSTPONE GT1 ; IMMEDIATE  ok
>> : GT5 GT4 ;  ok
>> gt5 . 123  ok
>> see gt5
>> : GT5
>>     GT1 ; ok
>>
>> GT4 compiles GT1 into the definition of GT5
>>
>>   From your other post:
>>
>>   > If the word postponed is not immediate, then postpone is redundant.
>>   > .... FOO ... and
>>   > .... POSTPONE FOO ... is the same thing if the FOO is not immediate.
>>
>> is wrong too, POSTPONE is used for macros e.g.
>>
>> : RDROP POSTPONE R> POSTPONE DROP ;
>> : FOO RDROP ;  ok
>> see RDROP
>> : RDROP  [']
>>     r> >comp ['] drop >comp ; immediate ok
>> see FOO
>> : FOO
>>     r> drop ; ok
>>
>> Read the ANS spec for POSTPONE carefully
>>
>> --
>> Gerry


-- 
Gerry

Thread

POSTPONE behaviour Aliaksei Chapyzhenka <alex.drom@gmail.com> - 2015-11-24 21:18 -0800
  Re: POSTPONE behaviour Raimond Dragomir <raimond.dragomir@gmail.com> - 2015-11-24 22:00 -0800
    Re: POSTPONE behaviour Aliaksei Chapyzhenka <alex.drom@gmail.com> - 2015-11-24 22:15 -0800
      Re: POSTPONE behaviour Raimond Dragomir <raimond.dragomir@gmail.com> - 2015-11-24 22:54 -0800
        Re: POSTPONE behaviour Aliaksei Chapyzhenka <alex.drom@gmail.com> - 2015-11-24 23:09 -0800
        Re: POSTPONE behaviour Lars Brinkhoff <lars.spam@nocrew.org> - 2015-11-25 08:15 +0100
          Re: POSTPONE behaviour Raimond Dragomir <raimond.dragomir@gmail.com> - 2015-11-24 23:38 -0800
            Re: POSTPONE behaviour Lars Brinkhoff <lars.spam@nocrew.org> - 2015-11-25 08:46 +0100
              Re: POSTPONE behaviour Raimond Dragomir <raimond.dragomir@gmail.com> - 2015-11-25 00:04 -0800
            Re: POSTPONE behaviour rickman <gnuarm@gmail.com> - 2015-11-25 03:01 -0500
              Re: POSTPONE behaviour Raimond Dragomir <raimond.dragomir@gmail.com> - 2015-11-25 00:09 -0800
                Re: POSTPONE behaviour rickman <gnuarm@gmail.com> - 2015-11-25 03:23 -0500
                Re: POSTPONE behaviour Raimond Dragomir <raimond.dragomir@gmail.com> - 2015-11-25 01:09 -0800
                Re: POSTPONE behaviour rickman <gnuarm@gmail.com> - 2015-11-25 10:49 -0500
                Re: POSTPONE behaviour "Elizabeth D. Rather" <erather@forth.com> - 2015-11-25 09:10 -1000
                Re: POSTPONE behaviour Gerry Jackson <gerry@jackson9000.fsnet.co.uk> - 2015-11-25 09:18 +0000
                Re: POSTPONE behaviour Raimond Dragomir <raimond.dragomir@gmail.com> - 2015-11-25 02:21 -0800
                Re: POSTPONE behaviour Mark Wills <markwills1970@gmail.com> - 2015-11-25 02:47 -0800
                Re: POSTPONE behaviour Gerry Jackson <gerry@jackson9000.fsnet.co.uk> - 2015-11-25 13:58 +0000
                Re: POSTPONE behaviour Mark Wills <markwills1970@gmail.com> - 2015-11-25 06:35 -0800
                Re: POSTPONE behaviour Bernd Paysan <bernd.paysan@gmx.de> - 2015-11-25 18:45 +0100
                Re: POSTPONE behaviour Raimond Dragomir <raimond.dragomir@gmail.com> - 2015-11-25 22:11 -0800
                Re: POSTPONE behaviour Gerry Jackson <gerry@jackson9000.fsnet.co.uk> - 2015-11-26 07:42 +0000
                Re: POSTPONE behaviour "Rod Pemberton" <boo@fasdfrewar.cdm> - 2015-11-26 05:20 -0500
                Re: POSTPONE behaviour anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-11-26 16:50 +0000
                Re: POSTPONE behaviour Gerry Jackson <gerry@jackson9000.fsnet.co.uk> - 2015-11-26 17:59 +0000
                Re: POSTPONE behaviour Bernd Paysan <bernd.paysan@gmx.de> - 2015-11-27 19:07 +0100
                Re: POSTPONE behaviour anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-11-28 11:24 +0000
                Re: POSTPONE behaviour hughaguilar96@gmail.com - 2015-11-26 12:29 -0800
                Re: POSTPONE behaviour Gerry Jackson <gerry@jackson9000.fsnet.co.uk> - 2015-11-27 09:53 +0000
                Re: POSTPONE behaviour hughaguilar96@gmail.com - 2015-11-29 21:48 -0800
                Re: POSTPONE behaviour Gerry Jackson <gerry@jackson9000.fsnet.co.uk> - 2015-11-30 12:18 +0000
                Re: POSTPONE behaviour Lars Brinkhoff <lars.spam@nocrew.org> - 2015-11-30 13:41 +0100
                Re: POSTPONE behaviour hughaguilar96@gmail.com - 2015-11-30 19:56 -0800
                Re: POSTPONE behaviour Gerry Jackson <gerry@jackson9000.fsnet.co.uk> - 2015-12-01 09:59 +0000
                Re: POSTPONE behaviour hughaguilar96@gmail.com - 2015-12-01 22:46 -0800
                Re: POSTPONE behaviour Gerry Jackson <gerry@jackson9000.fsnet.co.uk> - 2015-12-02 07:50 +0000
              Re: POSTPONE behaviour anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2015-11-25 13:45 +0000
                Re: POSTPONE behaviour rickman <gnuarm@gmail.com> - 2015-11-25 10:54 -0500
        Re: POSTPONE behaviour Gerry Jackson <gerry@jackson9000.fsnet.co.uk> - 2015-11-25 07:39 +0000
          Re: POSTPONE behaviour Aliaksei Chapyzhenka <alex.drom@gmail.com> - 2015-11-24 23:48 -0800
            Re: POSTPONE behaviour Gerry Jackson <gerry@jackson9000.fsnet.co.uk> - 2015-11-25 08:03 +0000
    Re: POSTPONE behaviour Bernd Paysan <bernd.paysan@gmx.de> - 2015-11-25 18:37 +0100
  Re: POSTPONE behaviour "Rod Pemberton" <boo@fasdfrewar.cdm> - 2015-11-25 01:27 -0500
    Re: POSTPONE behaviour Aliaksei Chapyzhenka <alex.drom@gmail.com> - 2015-11-24 22:51 -0800
  Re: POSTPONE behaviour Aliaksei Chapyzhenka <alex.drom@gmail.com> - 2015-11-25 21:19 -0800

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