Re: Back & Forth - Co-routines

On 31-01-2025 08:33, dxf wrote:

On 31/01/2025 4:42 am, Hans Bezemer wrote:

The lot of you have contributed to this episode - by discussing the previous episode on local variables.
>
I thank you for your comments - and decided it was worth its own episode: https://youtu.be/FH4tWf9vPrA
>
More than worth! ;-)

 Thanks Hans!
 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 ?

I'm sure it works - but IMHO it heavily depends on whether those words are primitives or not. E.g. in 4tH this expends to:
: local r> rot rot dup @ over >r >r ! ;: r> r> ! ;
And if I want to be pedantic, I have to include two SWAPs as well for the proper definition of 2>R and 2R>  - not to mention that you sometimes *DON'T* want to initialize your locals.
Another (consequential) disadvantage of this definition is that you have to *DEFINE* your words in reverse - a drawback which it shares with the original ANS LOCALS wordset.
Anyways, it may be useful to some people. Since I tend to use my LOCALs in conjunction with the 4tH preprocessor, I stick with the old version. It runs this one unmodified:
: LT1  {: a b | c -- f :}
    CR ." Hello1 " CR  a  ;
T{ 3 4 LT1 => 3 }T \ Outputs Hello1
: LT2  {: a | b c e :}
    CR ." Hello2 " CR  ;
T{ 3 LT2 => }T \ Outputs Hello2
: LT3  {: a b c -- :}
    CR ." Hello3 " CR  ;
T{ 3 4 5 LT3 => }T \ Outputs Hello3
: LT4  {: a b c :}
    CR ." Hello4 " CR  ;
T{ 3 4 5 LT4 => }T \ Outputs Hello4
: LT5  {: a | b c d -- e f g :}
    CR ." Hello5 " CR
    a 2* to b  b 2* to c  c 2* to d
    b c d  ;
T{ 3 LT5 => 6 12 24 }T \ Outputs Hello5
But as usual - thanks to the feedback!
Hans Bezemer