[Issue 1661] New: Not possible to specialize on template with integer parameter

[d-bugmail at puremagic.com]

http://d.puremagic.com/issues/show_bug.cgi?id=1661

           Summary: Not possible to specialize on template with integer
                    parameter
           Product: D
           Version: 1.023
          Platform: PC
        OS/Version: Windows
            Status: NEW
          Severity: major
          Priority: P2
         Component: DMD
        AssignedTo: bugzilla at digitalmars.com
        ReportedBy: wbaxter at gmail.com


If you have a template that takes an integer parameter, there appears to be no
way to specialize on that integer.

Here are some examples of things that work and things that don't:

/*==========================================================================
 * specialize.d
 *    Written in the D Programming Language (http://www.digitalmars.com/d)
 */
/***************************************************************************
 * Test of specialization in D templates
 *
 * <TODO: Description>
 *
 * Author:  William V. Baxter III
 * Date: 13 Nov 2007
 * License: Public Domain
 */
//===========================================================================

module specialize;
import std.stdio;
import std.string;

struct Container(Scalar,int N)
{
    Scalar[N] values_;
}

template Container2(T) { alias Container!(T,2) Container2; }

struct Simple(T) {
    T[] data;
}

struct Number(int N) {
    const int value = N;
}

void test_specialize(T)() {
    writefln("Not so special: ", typeid(T));
}
void test_specialize(T : float)() {
    writefln("special - float");
}
void test_specialize(T : T[U], U)() {
    writefln("special - Assoc Array of %s -> %s", typeid(U), typeid(T));
}
void test_specialize(T : Container!(T,3))() {
    writefln("Ooh special - CONTAINER T,3");
}
void test_specialize(T : Simple!(T))() {
    writefln("Ooh special - SIMPLE");
}
void test_specialize(T : Number!(2))() {
    writefln("Ooh special - NUMBER = 2");
}

// Cases that don't match

// This doesn't compile
//void test_specialize(T : Number!(int N), int N)() {
//    writefln("Ooh special - NUMBER");
//}
void test_specialize(T : Number!(N), int N)() {
    writefln("Ooh special - NUMBER N");
}
void test_specialize(T : Container2!(T))() {
    writefln("Ooh special - Container2!(T)");
}
void test_specialize(T : Container!(T,N), int N)() {
    writefln("Ooh special - Container!(T,N)");
}


void main() {
    test_specialize!(int)();
    test_specialize!(float)();
    test_specialize!(float[int])();
    test_specialize!(Simple!(int))();
    test_specialize!(Number!(2))();
    test_specialize!(Container!(int,3))();

    // These don't get matched
    test_specialize!(Number!(5))();
    test_specialize!(Container!(int,2))();
    test_specialize!(Container!(int,4))();

}


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