[REBOL] Re: The complete Rebol named argument passing
From: g:santilli:tiscalinet:it at: 1-Mar-2004 17:03
Hi Romano,
On Monday, March 1, 2004, 4:19:32 PM, you wrote:
>> RPT> do-alt find /reverse false
>>
>> RPT> find/alt /reverse false
>>
>> You can't have that, the best we could get is:
RPT> I think that both are possible. I prefer the first one.
There's no way to do that, REBOL needs to know the number of
arguments to process BEFORE actually starting to collect them.
Even if you were going to change the interpreter to allow
something like that, you'd have two issues: 1) ambiguity and 2)
not being expression based anymore.
Ambiguity:
f: func [x /ref] [...]
g: func [x /ref] [...]
f g x /ref
Does /ref belong to F or G? You need to parenthesize all
expressions.
No more expression based:
f x either cond [/ref] [none]
would you expect this to work? If not, your proposal is useless,
as you can't propagate refinements anyway. If yes, you have no way
to know that you have to evaluate the next expression without
knowing that it will return a REFINEMENT! value. If you evaluate
it and it does not return a refinement, you have evaluated the
expressions in the wrong order. If you don't and it would have
returned a refinement you are calling the function without all
arguments. To solve this you'd need to parenthesize all
expressions.
Regards,
Gabriele.
--
Gabriele Santilli <[g--santilli--tiscalinet--it]> -- REBOL Programmer
Amiga Group Italia sez. L'Aquila --- SOON: http://www.rebol.it/
