• Oliver <ruebenko imtek.de> Sep 17 2007
• Downs <default_357-line yahoo.de> Sep 17 2007
• Regan Heath <regan netmail.co.nz> Sep 17 2007

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

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
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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