• Marcone (2/2) Jan 16 2021 For example, I want my function template to only accept integer
• Ferhat =?UTF-8?B?S3VydHVsbXXFnw==?= (16/18) Jan 16 2021 There are different ways of doing that. I'd say this one is easy
• Basile B. (25/27) Jan 16 2021 You can do that with either

Marcone <marcone email.com> writes:

For example, I want my function template to only accept integer 
or string;

Ferhat =?UTF-8?B?S3VydHVsbXXFnw==?= <aferust gmail.com> writes:

On Saturday, 16 January 2021 at 18:39:03 UTC, Marcone wrote:
 For example, I want my function template to only accept integer 
 or string;

There are different ways of doing that. I'd say this one is easy 
to follow:

import std.stdio;

void print(T)(T entry) if(is(T==string) || is(T==int))
{
	writeln(entry);

}

void main(){
     int i = 5;
     string foo = "foo";

     double j = 0.6;

     print(i);
     print(foo);
     print(j); // compilation error
}

Basile B. <b2.temp gmx.com> writes:

On Saturday, 16 January 2021 at 18:39:03 UTC, Marcone wrote:
 For example, I want my function template to only accept integer 
 or string;

You can do that with either

- `static if` inside the body [1]

   import std.traits;
   void foo(T)(T t)
   {
     static if (isIntegral!T) {}
     else static assert false;
   }


- template constraint [2]

   import std.traits;
   void foo(T)(T t)
   if (isIntegral!T)
   {
   }

- template parameter specialization [3]

   void foo(T : ulong)(T t) // : meaning implictly convert to
   {
   }


2 and 3 being the more commonly used.
1 is more to use the same body instead of using N overloads

[1] : https://dlang.org/spec/version.html#staticif
[2] : https://dlang.org/spec/template.html#template_constraints
[3] : 
https://dlang.org/spec/template.html#parameters_specialization