• MrSmith (43/43) Sep 12 2014 Given the following program:
• =?UTF-8?B?QWxpIMOHZWhyZWxp?= (10/25) Sep 12 2014 TemplateArgsOf:
• MrSmith (2/31) Sep 12 2014 Thank you, Ali. I will try to not mismatch open tabs next time =)
• anonymous (27/70) Sep 12 2014 `is(...)` checks for types. firstInstance isn't a type, it's a

"MrSmith" <mrsmith33 yandex.ru> writes:

Given the following program:

---------------------------------
import std.stdio;

template first(string s)
{
	string first(string par)
	{
		if (par == s)
			return "true";
		else
			return "false";
	}
}

template second(alias firstInstance)
{
	string second(string par)
	{
		// this line doesn't work
		static if (is(firstInstance : F!(str), alias F, string str))
		{
			writeln("matched ", str);
		}
		
		enum s = "XXX"; // get s from firstInstance
		// without parsing strings and using mixins
		// something like second(alias C : F!(str), alias F, string str)
		
		import std.string : icmp;
		if (icmp(par, s) == 0)
			return "true";
		else
			return "false";
	}
}

void main()
{
	writeln(first!"str"("str"));
	writeln(second!( first!"str" )("StR")); // should match string 
from first, but case insensetive
}

---------------------------------

How do I extract s parameter of first passed to second via alias 
parameter. It seems like it is not possible. Or is it?

=?UTF-8?B?QWxpIMOHZWhyZWxp?= <acehreli yahoo.com> writes:

On 09/12/2014 12:44 PM, MrSmith wrote:

 Given the following program:

 ---------------------------------
 import std.stdio;

 template first(string s)
 {
      string first(string par)
      {
          if (par == s)
              return "true";
          else
              return "false";
      }
 }

 template second(alias firstInstance)
 {

TemplateArgsOf:

         import std.traits;
         foreach (i, arg; TemplateArgsOf!firstInstance) {
             writefln("arg %s: %s", i, arg);
         }

Prints:

arg 0: str

Ali

P.S. We want to see these topics over at the D.learn newsgroup. ;)

"MrSmith" <mrsmith33 yandex.ru> writes:

On Friday, 12 September 2014 at 20:37:44 UTC, Ali Çehreli wrote:
 On 09/12/2014 12:44 PM, MrSmith wrote:

 Given the following program:

 ---------------------------------
 import std.stdio;

 template first(string s)
 {
      string first(string par)
      {
          if (par == s)
              return "true";
          else
              return "false";
      }
 }

 template second(alias firstInstance)
 {

 TemplateArgsOf:

         import std.traits;
         foreach (i, arg; TemplateArgsOf!firstInstance) {
             writefln("arg %s: %s", i, arg);
         }

 Prints:

 arg 0: str

 Ali

 P.S. We want to see these topics over at the D.learn newsgroup. 
 ;)

Thank you, Ali. I will try to not mismatch open tabs next time =)

"anonymous" <anonymous example.com> writes:

On Friday, 12 September 2014 at 19:44:28 UTC, MrSmith wrote:
 Given the following program:

 ---------------------------------
 import std.stdio;

 template first(string s)
 {
 	string first(string par)
 	{
 		if (par == s)
 			return "true";
 		else
 			return "false";
 	}
 }

 template second(alias firstInstance)
 {
 	string second(string par)
 	{
 		// this line doesn't work
 		static if (is(firstInstance : F!(str), alias F, string str))

`is(...)` checks for types. firstInstance isn't a type, it's a
function, so the `is` expression is always false. You can use
std.traits.TemplateArgsOf instead:

                  import std.traits;
                  import std.typetuple;
                  static if(__traits(compiles,
TemplateArgsOf!firstInstance))
                  {
                      alias targs = TemplateArgsOf!firstInstance;
                      static if(is(typeof(targs) ==
TypeTuple!string))
                          writeln("matched ", targs[0]);
                  }

 		{
 			writeln("matched ", str);
 		}
 		
 		enum s = "XXX"; // get s from firstInstance
 		// without parsing strings and using mixins
 		// something like second(alias C : F!(str), alias F, string 
 str)

You're on the right track:

template second(alias C : F!(str), alias F, string str)
{
          string second(string par)
          {
                  import std.string : icmp;
                  if (icmp(par, str) == 0)
                          return "true";
                  else
                          return "false";
          }
}
	
 		import std.string : icmp;
 		if (icmp(par, s) == 0)
 			return "true";
 		else
 			return "false";
 	}
 }

 void main()
 {
 	writeln(first!"str"("str"));
 	writeln(second!( first!"str" )("StR")); // should match string 
 from first, but case insensetive
 }

 ---------------------------------

 How do I extract s parameter of first passed to second via 
 alias parameter. It seems like it is not possible. Or is it?