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From: Ruvim <ruvim.pinka@gmail.com>
Newsgroups: comp.lang.forth
Subject: Re: Back & Forth - Co-routines
Date: Sat, 1 Feb 2025 15:19:21 +0400
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On 2025-01-31 11:33, dxf wrote:
> 
> Not sure if previously mentioned but here's another version of LOCAL
> 
> : ;:  >r ;
> 
> : LOCAL ( x adr -- )
>    r> -rot dup @ over 2>r ! ;: 2r> ! ;
> 
> variable A  variable B  8 a !  7 b !
> 
> : divide ( a b -- )  b local  a local
>    a @  b @  /  . cr  ;
> 
> 15 3 divide  a ? b ?
> 


This approach does not work well with catch/throw. Because `throw` must 
restore the values of all "local" variables that are used in the 
definitions whose execution is being terminated. And this is difficult 
to implement.


See also 13.3.3.1, item c,
<https://forth-standard.org/standard/locals#subsubsection.13.3.3.1>

| ABORT shall release all local storage resources,
| and CATCH / THROW (if implemented) shall release
| such resources for all definitions whose execution
| is being terminated.


--
Ruvim