On 2025-11-05 08:46, Martin Nicholas via Amforth-devel wrote:
On Sun, 02 Nov 2025 14:40:07 +0000
CUT
You didn't ask for them, but I have a couple of ideas for
amforth-shell.py:
1.
Have an "#ifndef FORTHWORD forthword.frt" directive. "#ifdef" also.
2.
Directives that take a path or filename will look for a partial path.
i.e: #require project1/main.frt
#require project2/main.frt
are considered different files.
If either of these can be achieved by some other means, then please
chip in. I am aware of "#cd".
Hi Martin,
Thank you. Ideas are always welcome, and yours are very timely.
For 1. There might be an AmForth way or an amforth-shell way. Depends
upon what we want to use #ifdef for.
AmForth way - with a "bigger" Forth than AmForth there would be the
option of using [IF]..[ELSE]..[THEN]. AmForth does not have these
extension words from [1] but it does have [DEFINED] and [UNDEFINED].
From [2] on the website, a limited (by current SOURCE) Conditional
Interpret can be achieved.
|S| 1|anew empty
|W| 2|
|S| 3|: ?\ ( f -- ) if postpone \ then ; immediate
|W| 4|
|S| 5|[defined] 3+ 0= ?\ : xx 3+ ;
|S| 6|[undefined] 3+ 0= ?\ : xx 2 + ;
|W| 7|
|S| 8|100 xx . cr
|O| 8|102
|W| 9|
|S| 10|: 3+ ( n -- n ) 3 + ;
|W| 11|
|S| 12|[defined] 3+ 0= ?\ : yy 3+ ;
|S| 13|[undefined] 3+ 0= ?\ : yy 2 + ;
|W| 14|
|S| 15|100 yy . cr
|O| 15|103
I *think* this can be extended a little
|S| 17|anew empty
|W| 18|
|S| 19|: ifdef postpone [defined] invert if postpone \ then ;
immediate
|S| 20|: ifndef postpone [undefined] invert if postpone \ then ;
immediate
|W| 21|
|S| 22|: zz
|S| 23| ifdef 3+ 3+
|S| 24| ifndef 3+ 2 +
|S| 25|;
|W| 26|
|S| 27|100 zz . cr
|O| 27|102
|W| 28|
|S| 29|: 3+ ( n -- n ) 3 + ;
|W| 30|
|S| 31|: zz
|S| 32| ifdef 3+ 3+
|S| 33| ifndef 3+ 2 +
|S| 34|;
|W| 35|
|S| 36|100 zz . cr
|O| 36|103
I've not tested this beyond the snippet above. It's not
[IF]..[ELSE]..[THEN] by a long chalk but it's "all Forth" and it might
do the job. Alternatively,
amforth-shell way - amforth-shell does some [pre|post]processing of
serial streams to/from the mcu and can also interact using Forth with
the mcu. However, it has no conditional i.e. #ifdef ... capability.
This is something I've wanted, but I've been putting off as
(a) amforth-shell.py is very reliable and I don't want to break it
(b) the serial "handshaking" needed is not easy - goto (a)
Recently, however, I have merged amforth-shell with a preprocessor. I've
just added your idea, but renamed #ifdef to #ifword as #ifdef taken.
Forth source can look like this. #dictionary queries mcu and fills local
cache, #ifword queries local cache.
anew empty
#dictionary
: zz
#ifword 3+
3+
#else
2 +
#endif
;
100 zz . cr
: 3+ ( n -- n ) 3 + ;
#dictionary
: zz
#ifword 3+
3+
#else
2 +
#endif
;
100 zz . cr
which when uploaded to the mcu it looks like this. You only get to "see"
what was left after the preprocessor has done its work.
|S| 1|anew empty
|S| 2|: zz
|S| 3| 2 +
|S| 4|;
|S| 5|100 zz . cr
|O| 5|102
|S| 6|: 3+ ( n -- n ) 3 + ;
|S| 7|: zz
|S| 8| 3+
|S| 9|;
|S| 10|100 zz . cr
|O| 10|103
It needs a lot more testing before it goes anywhere near the repo. If
you are willing to alpha test it, I will tidy it up.
Best wishes,
Tristan
[1] 15.6.2 Programming-Tools extension words
https://forth-standard.org/standard/tools
[2]
https://amforth.sourceforge.net/TG/recipes/Conditional-Interpret.html
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