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digitalmars.D.learn - Function accepting variadic arguments

reply pineapple <meapineapple gmail.com> writes:
I'd like to make a constructor which takes a variable list of 
arguments, of a short list of possible types, with different 
handling depending on the type. I haven't been able to find any 
documentation or examples that did quite what I'm trying to. Help?

A fun pseudocode example of what I'm trying to do:

this(...){
     foreach(argument){
         if(argument is a number){
             do stuff with it;
         }else if(argument is of type A){
             do other stuff;
         }else if(argument is of type B){
             yet more stuff;
         }
     }
}
Jan 20
next sibling parent reply =?UTF-8?Q?Ali_=c3=87ehreli?= <acehreli yahoo.com> writes:
On 01/20/2016 04:38 AM, pineapple wrote:
 I'd like to make a constructor which takes a variable list of arguments,
 of a short list of possible types, with different handling depending on
 the type. I haven't been able to find any documentation or examples that
 did quite what I'm trying to. Help?

 A fun pseudocode example of what I'm trying to do:

 this(...){
      foreach(argument){
          if(argument is a number){
              do stuff with it;
          }else if(argument is of type A){
              do other stuff;
          }else if(argument is of type B){
              yet more stuff;
          }
      }
 }
import std.stdio; struct A { double d; } struct B { string s; } struct C { this(T...)(T args) { foreach (arg; args) { static if (is (typeof(arg) == int)) { writefln("int: %s", arg); } else static if (is (typeof(arg) == A) ) { writefln("A: %s", arg); } else static if (is (typeof(arg) == B)) { writefln("B: %s", arg); } } } } void main() { auto c = C(42, A(1.5), B("hello")); } Prints: int: 42 A: A(1.5) B: B("hello") And there is another example here: http://ddili.org/ders/d.en/templates_more.html#ix_templates_more.tuple%20template%20parameter Ali
Jan 20
parent reply pineapple <meapineapple gmail.com> writes:
On Wednesday, 20 January 2016 at 12:56:51 UTC, Ali Çehreli wrote:
 And there is another example here:


 http://ddili.org/ders/d.en/templates_more.html#ix_templates_more.tuple%20template%20parameter

 Ali
Thank you! What's the purpose of "is" in the type checks? Also, how would I utilize isNumeric from std.traits here, in place of checking only for ints?
Jan 20
parent reply Daniel Kozak <kozzi11 gmail.com> writes:
On Wednesday, 20 January 2016 at 13:06:14 UTC, pineapple wrote:
 On Wednesday, 20 January 2016 at 12:56:51 UTC, Ali Çehreli 
 wrote:
 And there is another example here:


 http://ddili.org/ders/d.en/templates_more.html#ix_templates_more.tuple%20template%20parameter

 Ali
Thank you! What's the purpose of "is" in the type checks?
is is use for compare types
 Also, how would I utilize isNumeric from std.traits here, in 
 place of checking only for ints?
struct S { this(Args...)(Args args) { foreach(Index, Value;args) { if (isNumeric!(Args[index])) { ... } } } }
Jan 20
parent Daniel Kozak <kozzi11 gmail.com> writes:
On Wednesday, 20 January 2016 at 13:09:13 UTC, Daniel Kozak wrote:
 On Wednesday, 20 January 2016 at 13:06:14 UTC, pineapple wrote:
 On Wednesday, 20 January 2016 at 12:56:51 UTC, Ali Çehreli 
 wrote:
 And there is another example here:


 http://ddili.org/ders/d.en/templates_more.html#ix_templates_more.tuple%20template%20parameter

 Ali
Thank you! What's the purpose of "is" in the type checks?
is is use for compare types
 Also, how would I utilize isNumeric from std.traits here, in 
 place of checking only for ints?
struct S { this(Args...)(Args args) { foreach(Index, Value;args) { if (isNumeric!(Args[index])) { ... } } } }
isNumeric!(Args[index] should be: isNumeric!(Args[Index]
Jan 20
prev sibling parent reply Daniel Kozak via Digitalmars-d-learn <digitalmars-d-learn puremagic.com> writes:
V Wed, 20 Jan 2016 12:38:20 +0000
pineapple via Digitalmars-d-learn <digitalmars-d-learn puremagic.com>
napsáno:

 I'd like to make a constructor which takes a variable list of 
 arguments, of a short list of possible types, with different 
 handling depending on the type. I haven't been able to find any 
 documentation or examples that did quite what I'm trying to. Help?
 
 A fun pseudocode example of what I'm trying to do:
 
 this(...){
      foreach(argument){
          if(argument is a number){
              do stuff with it;
          }else if(argument is of type A){
              do other stuff;
          }else if(argument is of type B){
              yet more stuff;
          }
      }
 }
 
import std.stdio; struct S { this(Args...)(Args args) { foreach(Type, Value;args) { writefln("Type: %s value: %s", Args[Type].stringof, Value); } } } void main() { auto s = S(1, "string"); }
Jan 20
parent Daniel Kozak <kozzi11 gmail.com> writes:
On Wednesday, 20 January 2016 at 13:04:23 UTC, Daniel Kozak wrote:
 V Wed, 20 Jan 2016 12:38:20 +0000
 pineapple via Digitalmars-d-learn 
 <digitalmars-d-learn puremagic.com>
 napsáno:


 import std.stdio;

 struct S
 {
     this(Args...)(Args args)
     {
         foreach(Type, Value;args)
         {
             writefln("Type: %s value: %s", Args[Type].stringof, 
 Value);
         }
     }
 }

 void main()
 {
     auto s = S(1, "string");
 }
Type should be named Index :)
Jan 20