Re: Collective response to := messages

[sommar@enea.se (Erland Sommarskog)]

William Thomas Wolfe (billwolf@hubcap.clemson.edu) writes:
>I said:
>> Oh, someone thought that an user-defined ":=" should apply to parameter
>> passing as well. This is of course impossible. In that case ":=" should
>> define how the parameters were passed to itself. A true circular definition!
>
>    Recall the discussion.  The rule that the "old" version of assign
>    would apply throughout any function named ":=", including parameter
>    passing, handles this contingency.

So there should be one rule for passing parameters to ":=" and another
to all other subprograms? That, if nothing else, shows that there is
something wrong with the idea. You expect all subprograms to behave
the same. What if ":=" is renamed? Should the rules change? And if
":=" calls another subprogram, what rules should be applied in this
case?
  Unless you don't want to fill the language definition with special
cases, and I don't, the idea to have a user-defined ":=" to implicitly
define parameter passing seems dead. If you really want it that way
you should think of some new syntactic device for defining assignment
of a limited type.
-- 
Erland Sommarskog
ENEA Data, Stockholm
sommar@enea.se
"Frequently, unexpected errors are entirely unpredictable" - Digital Equipment