Function overloading

[Regan Heath]

Vladimir wrote:
> Ok, it works for that case.
> 
> I'm playing with string template parameters. It's a kind of miracle
> for me, a c++ programmer. I made a precompiled wildcard match and
> would like static version to overload as follows:
> 
> bool wildcardMatch (T : char[]) (T wild, T str) // general case { 
> return false; }
> 
> bool wildcardMatch (char[] W) (T str) // static case { return false; 
> }
> 
> void main() { wildcardMatch ("*", "123"); wildcardMatch !("*")
> ("123"); }
> 
> Is that posible?

At first I thought, maybe "static if" would be better than a template 
specialization, i.e.

bool wildcardMatch (T : char[]) (T wild, T str)
{
     static if (wild == "*") return true;
     return false;
}

but of course the value of 'wild' is not known at compile time... or is it?

If it's a constant as in your example 'main' above then it is and the 
compiler could theoretically evaluate it.

But then I thought, if you know it's "*" why make a call to 
wildcardMatch at all? (after all it will always match)

I came up with:

bool someOtherTpl (T : char[]) (T wild, T str, bool something)
{
   if (something)
     wildcardMatch(wild, str);
}

someOtherTpl("*", ...

which is a case where you have to code the call to wildcardMatch because 
you don't know wild was "*" at that point.


The closest I managed to get with template specialization is:

import std.stdio;

bool wildcardMatch (T) (T wild, T str) // general case
{
     writefln("general case");
     return false;
}

bool wildcardMatch (W:invariant(char[1]), S) (W wild, S str) // "*" case
{
     writefln("* case");
     return false;
}

void main()
{
     wildcardMatch!(char[])("*asd*".dup, "123".dup);
     wildcardMatch!(invariant(char[1]),char[])("*", "123".dup);
     wildcardMatch!(invariant(char[1]),char[])("a", "123".dup);
}

Which incorrectly calls the * case for the wild string "a" because of 
course it is specializing using a static array of 1 character.

Regan