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From: Kaz Kylheku <643-408-1753@kylheku.com>
Newsgroups: comp.lang.c
Subject: Re: Named arguments in C
Date: Thu, 4 Jul 2024 03:15:28 -0000 (UTC)
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On 2024-07-04, Keith Thompson <Keith.S.Thompson+u@gmail.com> wrote:
> bart <bc@freeuk.com> writes:
> [...]
>> It really needs language support. That has been done in C for
>> designated initialisers; named args are a similar feature, easier to
>> implement (they can only be one level deep for example) and IMO far
>> more useful.
>>
>> Although there are a few extra problems with C because the extra info
>> needed (parameter names and default values) can appear in both the
>> definition, and any number of prototype declarations, which cannot in
>> conflict.
>
> As I recall, we had this discussion here a while ago.  The fact that C
> allows parameter names for a function definition to differ from those in
> corresponding declarations is a bit inconvenient.  But what I recall
> suggesting at the time is that the parameter names in a call need to be
> consistent with the names in the visible declaration.
>
>     void foo(int x, int y) {
>         // ...
>     }
>
>     void foo(int xx, int yy);
>
>     foo(xx: 10, yy: 20);

void (*pfoo)(int y, int x) = foo;

pfoo(xx: 10, yy: 20); // oops, arguments are silently reversed

Before we have named arguments, we have to somehow make name part of the
type, so that the above pointer initialization violates a constraint.

Problem:

   void foo(int, int);

   void (*foo1)(int y, int x) = foo;

   void (*foo2)(int x, int y) = foo;

The crux is that parameters/arguments which are /simultaneously/ named /and/
positional are a bad idea.

Keyword parmeters should be a separate new category, specially
declared, and understood not to be ordered. There should be no way
to pass by-order arguments to keyword parameters.

-- 
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