Re: forward references

There are many approaches. Here's one:

10 CONSTANT #STATES
CREATE STATES #STATES CELLS ALLOT
VARIABLE MYSTATE

: STATE ( n -- ) MYSTATE @ 1- \ Provide for 1-relative
indexing
         0 MAX #STATES MIN \ Clip to within bounds
         CELLS STATES + @EXECUTE ; \ Perform function

: Main ( -- )
    1 MYSTATE !
    BEGIN
       KEY STATE
    AGAIN ;

: State1 ( event -- )
         somecode1 IF
                 2 MYSTATE !
         THEN :
' State1 STATES 0 CELLS + ! \ Note 0-relative index here

[etc.]

You might be able to avoid the bounds clipping by ensuring you write
all the code and you'll never set an illegal state. Also, you might prefer
to do everything zero-relative, and avoid the 1-

Cheers,
Elizabeth

At 05:44 PM 3/26/02 -0300, Nestor D. Closa wrote:

>How can you write states in forth without forward references ?
>
>VARIABLE 'MyState
>
>: State1 ( event -- )
> somecode1
> IF
> ['] State2 'MyState !
> THEN ;
>
>: State2 ( event -- )
> somecode2
> IF
> ['] State3 'MyState !
> THEN ;
>
>: State3 ( event -- )
> somecode3
> IF
> ['] State1 'MyState !
> THEN ;
>
>: Main ( -- )
> ['] State1 'MyState !
> BEGIN
> KEY 'MyState @EXECUTE
> AGAIN ;
>
>
>Nestor Closa
>
>
>
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==================================================
Elizabeth D. Rather (US & Canada) 800-55-FORTH
FORTH Inc. +1 310-491-3356
5155 W. Rosecrans Ave. #1018 Fax: +1 310-978-9454
Hawthorne, CA 90250
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applications since 1973."
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For help with listar commands, send subject "help" to listar_at_forth.com
Archives are located at http://www.forth.com/swiftx -- check them out!
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THIS LIST IS NOT FOR BUG REPORTS! Send bug reports to support_at_forth.com.
Received on Tue Mar 26 2002 - 13:07:25 PST