Pretty please: Named arguments

[Steven Schveighoffer]

On Tue, 01 Mar 2011 04:10:12 -0500, Don <nospam at nospam.com> wrote:

> Steven Schveighoffer wrote:
>> On Mon, 28 Feb 2011 16:38:34 -0500, Don <nospam at nospam.com> wrote:
>>
>>> spir wrote:
>>>>  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).
>>  encounter *reading* it or encounter *using it*?  You shouldn't ever  
>> have to use named parameters if you don't want to.  Just like you can  
>> specify all defaulted parameters, or specify all template args when  
>> calling templated functions.
>>  I could live without named parameters (obviously!), but I certainly  
>> think reading a call with named parameters can be much easier with the  
>> parameter names than without, and I don't think you could ever say the  
>> opposite (that name-less parameters would be clearer).
>
> For sure they can be clearer with nameless parameters!
>
> printf(formatstr: "Hello World!\n");

This is not less clear than printf("Hello World!\n");   It's as clear.   
More verbose, yes, but clear.

Just like foo!int(1) is as clear as, but more verbose than, foo(1).

>> In essense, the parameter names are ALREADY an essential part of the  
>> API.  If we didn't name the parameters (entirely possible with .di  
>> files!), how shitty would programming be?
>
> The names are for humans to read. They are documentation. That's a big  
> difference.

And they continue to be documentation, I'm documenting what my argument  
names are at the call site so I don't have to go back to the function  
definition to determine what each parameter is via position.

Regarding your objection in another post, I see your point that you don't  
want to break existing code by changing a parameter name.  A way to look  
at this is, you must choose good parameter names on the first try.   
Another way to look at it is, I'm documenting my function call -- I want  
to be notified by the compiler when the parameter names changed because I  
want to reassure myself that the call is still valid.  My point is, the  
function author should choose good names, but if he must make a change,  
then fear of breaking calls should not dissuade him.  We routinely change  
the names of functions or deprecate them, this is taken in stride by the  
users of the library, I don't see how changing parameter names is any  
different.

-Steve