• Rick Mann (21/21) Feb 03 2007 I'm not sure I understand the matching rules for overloaded functions. I...
• Carlos Santander (6/39) Feb 03 2007 Instead of "import std.string" try "static import std.string", so you ca...
• Jarrett Billingsley (44/53) Feb 03 2007 I'm assuming that you've declared this type and toString function in a

Rick Mann <rmann-d-lang latencyzero.com> writes:

I'm not sure I understand the matching rules for overloaded functions. I have a
type:

typedef int OSStatus;

and I want to call

OSStatus err;
toString(err);

but I get these errors:

function std.string.toString called with argument types:
        (OSStatus)
matches both:
        std.string.toString(char)
and:
        std.string.toString(real)


It more readily matches toString(int). I realize the spec says that if a match
is ambiguous, then it's an error, but it sure would be nice if this worked.

So, I tried defining my own toString(OSStatus):

char[]
toString(OSStatus inVal)
{
	return std.string.toString(cast (int) inVal);
}


But I get the same error.

Can someone tell me why? Surely an exact match would be acceptable. Thanks!

Carlos Santander <csantander619 gmail.com> writes:

Rick Mann escribió:
 I'm not sure I understand the matching rules for overloaded functions. I have
a type:
 
 typedef int OSStatus;
 
 and I want to call
 
 OSStatus err;
 toString(err);
 
 but I get these errors:
 
 function std.string.toString called with argument types:
         (OSStatus)
 matches both:
         std.string.toString(char)
 and:
         std.string.toString(real)
 
 
 It more readily matches toString(int). I realize the spec says that if a match
is ambiguous, then it's an error, but it sure would be nice if this worked.
 
 So, I tried defining my own toString(OSStatus):
 
 char[]
 toString(OSStatus inVal)
 {
 	return std.string.toString(cast (int) inVal);
 }
 
 
 But I get the same error.
 
 Can someone tell me why? Surely an exact match would be acceptable. Thanks!

Instead of "import std.string" try "static import std.string", so you can only 
call std.string.toString by its FQN. Or import it privately and use your 
toString from another module (which doesn't import std.string)

-- 
Carlos Santander Bernal

"Jarrett Billingsley" <kb3ctd2 yahoo.com> writes:

"Rick Mann" <rmann-d-lang latencyzero.com> wrote in message 
news:eq2ssi$14jh$1 digitaldaemon.com...

 So, I tried defining my own toString(OSStatus):

 char[]
 toString(OSStatus inVal)
 {
 return std.string.toString(cast (int) inVal);
 }


 But I get the same error.

 Can someone tell me why? Surely an exact match would be acceptable. 
 Thanks!

I'm assuming that you've declared this type and toString function in a 
module which you're importing, since defining it in the same file that it's 
used works.

So say youd have your file ostypes.d:

module ostypes;

import std.string;

typedef int OSStatus;

char[] toString(OSStatus s)
{
    return std.string.toString(cast(int)s);
}


And then you import it from main.d:

module main;

import std.string;
import ostypes;

void main()
{
    A a = 6;
    writefln(toString(a));
}

You get the error that you quoted.  This is because D does not do function 
overloading across modules.  The answer I got as to why this happens is that 
"it's the way C++ does it."  I never quite understood that rationale. 
(Interestingly one of my very first threads in this newsgroup was about a 
problem very similar to yours!)

So you have to "bring in" the toString symbols into a module that imports 
modules with conflicting symbols.  You do this with aliases:

module main;

import std.string;
import ostypes;

alias std.string.toString toString;
alias ostypes.toString toString;

void main()
{
    A a = 6;
    writefln(toString(a));
}

You have to have an alias for each module that overloads the function and 
for each function that's overloaded in more than one module.  If you leave 
out the first alias (that brings in std.string.toString), you'll be able to 
use toString for your OSStatus type but not for any other types.

This is really ugly.