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digitalmars.D.learn - Template overloading

reply Oliver <ruebenko imtek.de> writes:
Hi everyone,

i would like to overload template functions. The following code shows what i'd
like. 

import std.stdio;

void test(T1)(T1 n1) {
    writefln("number: ", n1); }

void test(T2)(T2[] array ) {
    writefln("array: ", array); }


void main () {
    double d1 = 2.1;
    double d2 = 1.2;
    double[] da1 = [d1, d2];

    test(d1);
    test(da1);
}

This fails (to my understanding) because the templates are not specialized
enough. Is it possible to specialize the template to either accept an array of
numbers (of any type) or a single number (of any type). 

Any comments are appreciated. Thanks
Sep 17 2007
next sibling parent Downs <default_357-line yahoo.de> writes:
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Hash: SHA1

Oliver wrote:
 Hi everyone,
 
 i would like to overload template functions. The following code shows what i'd
like. 
 
 import std.stdio;
 
 void test(T1)(T1 n1) {
     writefln("number: ", n1); }
 
 void test(T2)(T2[] array ) {
     writefln("array: ", array); }
 
 
 void main () {
     double d1 = 2.1;
     double d2 = 1.2;
     double[] da1 = [d1, d2];
 
     test(d1);
     test(da1);
 }
 
 This fails (to my understanding) because the templates are not specialized
enough. Is it possible to specialize the template to either accept an array of
numbers (of any type) or a single number (of any type). 
 
 Any comments are appreciated. Thanks

The only way I can see to do this is with static if e.g. import std.stdio; template isArray(T) { const bool isArray=false; } template isArray(T: T[]) { const bool isArray=true; } void test(T)(T n) { static if(isArray!(T)) writefln("array: ", n); else writefln("number: ", n); } --downs -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.7 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFG7la9pEPJRr05fBERAhuxAKCX1WF6s3UxK3c1tznI5WG2Wg+IswCdGyBl UAkz2n9mGqR1sMRpVpV4xZI= =8UpJ -----END PGP SIGNATURE-----
Sep 17 2007
prev sibling parent Regan Heath <regan netmail.co.nz> writes:
Oliver wrote:
 Hi everyone,
 
 i would like to overload template functions. The following code shows what i'd
like. 
 
 import std.stdio;
 
 void test(T1)(T1 n1) {
     writefln("number: ", n1); }
 
 void test(T2)(T2[] array ) {
     writefln("array: ", array); }
 
 
 void main () {
     double d1 = 2.1;
     double d2 = 1.2;
     double[] da1 = [d1, d2];
 
     test(d1);
     test(da1);
 }
 
 This fails (to my understanding) because the templates are not
 specialized enough. Is it possible to specialize the template to
 either accept an array of numbers (of any type) or a single number
 (of any type).
 
 Any comments are appreciated. Thanks

My first instinct is to try this: void test(T2 : T2[])(T2[] array ) { writefln("array: ", array); } but, just like every other time I have tried to use template specialization I find that I cannot also use argument deduction: template <file>.test(T : T[]) specialization not allowed for deduced parameter T Granted the work around is simply to not use argument deduction but it's a real PITA. Regan
Sep 17 2007