Overload resolution for string

[Steven Schveighoffer]

On Mon, 12 Apr 2010 00:40:44 -0400, Ali Çehreli <acehreli at yahoo.com> wrote:

> Steven Schveighoffer wrote:
>  > On Sun, 11 Apr 2010 15:33:09 -0400, Ali Çehreli <acehreli at yahoo.com>  
> wrote:
>  >
>  >> This is a bug, right? I've been assuming that unqualified string
>  >> literals were immutable char arrays, but the behavior is different
>  >> between "hello" vs. "hello"c.
>  >>
>  >> Am I missing something?
>  >
>  > "hello" is typed as a string *only* if you are using at a string.  If
>  > you are using it as a wstring or a dstring, then it is typed that way.
>  > You can even use it as a const(char) * and it becomes an ASCII C-style
>  > string with a zero terminator!
>
> I did not know that. :)
>
> Could you please share some guidelines about chosing the type of the  
> D-string to use at the interface...
>
> Should applications stick to one of these types and require callers to  
> convert explicitly if needed? Should the common type be dstring? On the  
> other hand, string seems to be a better choice because classes have the  
> common toString member functions that return string.
>
> In my case, I have a set of classes that represent alphabet letters and  
> alphabet strings. The motivation is to provide logical sorting and  
> capitalization. (To me, even for the English alphabet, â should be  
> sorted between a and b.)
>
> Since I want these types to be used as seamlessly as possibly, I wanted  
> to provide opEquals overloads for char[], wchar[], and dchar[]. Should I  
> not bother doing that? In fact, I really shouldn't due to this compiler  
> error.
>
> Should my classes only interface with dchar and dstring?

If you had to choose, I'd suggest choosing string.  The reason is simple:

auto s = "hello";
yourFunc(s);

Because the compiler must choose a type when declaring s, it chooses  
string.

I think perhaps the compiler should use the same rules when calling an  
overloaded function with a literal.  You should file an enhancement  
request with bugzilla, see what Walter thinks.  If he doesn't like the  
idea, he usually shoots it down pretty quick :)

-Steve