Re: 0 SET-ORDER why?

On 27/06/2024 20:22, Krishna Myneni wrote:

On 6/27/24 14:09, Krishna Myneni wrote:

On 6/26/24 23:14, Gerry Jackson wrote:

On 26/06/2024 14:36, Ruvim wrote:

One possible use case:
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   : turnkey ( -- ) 0 set-order
     also Target definitions
     also Minimal also
   ;

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ALSO duplicates the wordlist at the head of the search order. If the search order is empty there is nothing to duplicate. Therefore ALSO applied to an empty search order ought to be an ambiguous condition.
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Presumably the above definition works because a target wordlist replaces whatever garbage ALSO leaves in the search order. So the definition might as well have 0 1 SET-ORDER instead of 0 SET-ORDER ALSO.
Or better still TARGET-WORDLIST 1 SET-ORDER. Either removes the above justification for 0 SET-ORDER.
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Good analysis showing that
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1) The definition of TURNKEY is flawed.
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2) 0 SET-ORDER is not necessary.
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But having said that it is better for 0 SET-ORDER to do what is natural instead of yet another ambiguous condition.
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 > Another possible use case:
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 >    : s-to-n ( addr u -- n )
 >      depth >r
 >      get-order n>r 0 set-order
 >        ['] evaluate ['] execute-interpreting catch
 >      nr> set-order
 >      depth 1- r> <> if -12 throw then
 >    ;
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This is a better use case e.g. if BASE is greater than decimal 10 converting an alphanumeric string to a number could clash with a word in the dictionary. Having an empty search order eliminates that possibility.
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This use case is convoluted and there may be a better of dealing with the anticipated problem.
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It has been a real problem, years ago I compiled some preset data in Hex (before the $ prefix was standardised). Something like A5 c, 13 c, D0 c, ...
and the application worked on a number of systems and then crashed on another standard system. On investigation I found that D0 was a defined word in that system - hence a crash. OK the $ prefix solves that but not the general problem e.g. BASE = #24 say

If not, we should consider what's missing in Forth allowing us to solve the problem more directly.
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No one has pointed to a need for 0 SET-ORDER in interpretation state, and there is no to undo its use in interpretation state in a standard. Furthermore an empty search order contradicts the concept of a minimum search order.
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The solutions are:
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1) leave everything as is, and live with the contradiction and the hazard of performing 0 SET-ORDER in interpretation state.

I favour  this, there are other ways of achieving the effect of
0 SET-ORDER in interpretation mode, for example
1) WORDLIST 1 SET-ORDER
2)  Using PREVIOUS on a search order of FORTH-WORDLIST only (assuming FORTH-WORDLIST contains PREVIOUS)
3) ...
I suspect trying to ban every possibility isn't worth it

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2) make SET-ORDER state-smart, and live with the contradiction. This will potentially break code.
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3) disallow zero as an argument to SET-ORDER e.g. throw an error for zero.
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Am I missing any other options?
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Personally, I favor 3) -- throwing an error when zero is an argument to SET-ORDER.
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 Edits:
 No one has pointed to a need for 0 SET-ORDER in interpretation state,
and there is no standard way to undo its use in interpretation state.
 3) disallow zero as an argument to SET-ORDER e.g. throw an error for zero. This will break existing code where zero is an argument to SET-ORDER.
 Any idea of frequency of usage for 0 SET-ORDER . I don't believe I have ever used it in a definition.
 -- KM
 

--
Gerry