Pretty please: Named arguments

[Don]

spir wrote:
> On 02/28/2011 07:51 PM, Jonathan M Davis wrote:
>> I'm not entirely against named arguments being in D, however I do 
>> think that any
>> functions that actually need them should be refactored anyway.

I agree.
CreateFont() in the Windows API, I'm looking at you. (For Linux people, 
that function has about 12 parameters).


> ???
> 
>> In actuality, if I were to vote on whether named arguments should be 
>> in the
>> language, I would definitely vote against it (I just plain don't want 
>> the code
>> clutter,  [...]
> 
> Just don't use them!

You don't have that option. At least, if you're a library developer, you 
don't. (I'm a bit sick of people saying "you don't have to use it if you 
don't want to" in language design. If it is in the language, you don't 
have a choice. You will encounter it).

There are a couple of things that I really, really don't like about the 
names argument idea:
1. It makes parameter names part of the API.
Providing no way for the function writer to control whether it is part 
of the API or not, and especially, doing it retrospectively, strikes me 
as extremely rude.

2. It introduces a different syntax for calling a function.
foo(4, 5);
foo(x: 4, y: 5);
They look different, but they do exactly the same thing. I don't like 
that redundancy.


Especially since, as far as I can tell, the named arguments are just 
comments (which the compiler can check).
If so, a syntax like this would be possible, with no language change at all:

pragma(namedarguments); // applies to whole module

foo(/*x*/ 4, /*y*/ 5);

---> if a function parameter has a comment which forms a valid 
identifier, it's a named parameter.

But I still don't see the need for this feature. Aren't people using 
IDEs where the function signature (with parameter names) pops up when 
you're entering the function, and when you move the mouse over the 
function call?
And if you really want to see them all the time, why not build that 
feature into the IDE?
("hit ctrl-f9 to show all parameter names, hit it again to hide them").