On Sun, 29 Nov 2009 16:02:24 +0300, Lutger <lutger.blijdest...@gmail.com>
wrote:
biozic wrote:
Le 29/11/09 13:16, Michel Fortin a écrit :
On 2009-11-29 06:14:21 -0500, "Simen kjaeraas" <simen.kja...@gmail.com>
said:
That is because your opDispatch is instantiated no matter what the
name
is, but only does something sensible if it's foo. Try this:
string opDispatch( string name )( ) {
static if ( name == "foo" ) {
return "foo";
} else {
static assert( false, "Invalid member name." );
}
}
Wouldn't this be even better?
string opDispatch(string name)() if (name == "foo") {
return "foo";
}
I haven't tested that it works though.
It doesn't improve the error message, but it works. It's been a long
time since I used D: I didn't know this syntax!
Don has made a patch to improve these kind of error messages in
templates,
but that will probably come after D2 is finalized (doesn't affect the
language).
If you want to resolve the symbol at runtime I think you can get a better
error message for throwing an exception or assertion. I don't have the
svn
dmd, so this isn't tested:
void opDispatch(string name)(string file = __FILE__, int line = __LINE__)
{
if ( !dynamicDispatch(name) )
{
// line and file are default initialized from the call site:
throw new MethodMissingException(name, file, line);
}
}
IIRC, this trick only works when __FILE__ and __LINE__ are both template
arguments.
