• Manfred Nowak (14/14) May 22 2015 How can one determine the recursion depth for templated types?
• Matt Kline (4/18) May 22 2015 Why should the last line write SetSet? (It doesn't.) toString
• Manfred Nowak (4/5) May 22 2015 Correct. I do not know how to use `T' to determine the recursion depth o...
• Timon Gehr (18/23) May 22 2015 import std.stdio, std.range, std.algorithm;
• Manfred Nowak (3/7) May 22 2015 Thx. Seems that I have to relearn a lot.

Manfred Nowak <svv1999 hotmail.com> writes:

How can one determine the recursion depth for templated types?

Example code:

import std.stdio;
class Set(T){
  override string toString(){
    return "Set";
  }
}
void main(){
  auto s0= new Set!uint;
  writeln( s0); // writes Set

  auto s1= new Set!(Set!uint);
  writeln( s1); // should write SetSet
}

"Matt Kline" <matt bitbashing.io> writes:

On Friday, 22 May 2015 at 21:13:50 UTC, Manfred Nowak wrote:
 How can one determine the recursion depth for templated types?

 Example code:

 import std.stdio;
 class Set(T){
   override string toString(){
     return "Set";
   }
 }
 void main(){
   auto s0= new Set!uint;
   writeln( s0); // writes Set

   auto s1= new Set!(Set!uint);
   writeln( s1); // should write SetSet
 }

Why should the last line write SetSet? (It doesn't.) toString 
isn't making any use of the template argument T, so no recursion 
occurs.

Manfred Nowak <svv1999 hotmail.com> writes:

Matt Kline wrote:

 isn't making any use of the template argument T

Correct. I do not know how to use `T' to determine the recursion depth of 
the template---and I want no further parameter.

-manfred 

Timon Gehr <timon.gehr gmx.ch> writes:

On 05/23/2015 12:12 AM, Manfred Nowak wrote:
 Matt Kline wrote:

 isn't making any use of the template argument T

 Correct. I do not know how to use `T' to determine the recursion depth of
 the template---and I want no further parameter.

 -manfred

import std.stdio, std.range, std.algorithm;

template getDepth(T){
     static if(is(T==Set!S,S)) enum getDepth=1+getDepth!S;
     else enum getDepth=0;
}
class Set(T){
     override string toString(){
         enum r="Set".repeat.take(getDepth!Set).join;
         return r;
     }
}
void main(){
     auto s0=new Set!uint;
     writeln(s0); // writes Set
     auto s1=new Set!(Set!uint);
     writeln(s1); // writes SetSet
}

Manfred Nowak <svv1999 hotmail.com> writes:

Timon Gehr wrote:

 template getDepth(T){
      static if(is(T==Set!S,S)) enum getDepth=1+getDepth!S;
      else enum getDepth=0;
 }

Thx. Seems that I have to relearn a lot.

-manfred