• Joseph Rushton Wakeling (11/11) Apr 27 2012 Hello all,
• Simen Kjaeraas (25/35) Apr 27 2012 std.typecons has a type called Tuple, which is probably what you want:
• Joseph Rushton Wakeling (3/4) Apr 27 2012 ... !

Joseph Rushton Wakeling <joseph.wakeling webdrake.net> writes:

Hello all,

Just recently I tried returning a Tuple from a function and received an error 
message about this not being allowed.

Reading up a bit on the D site I'm not clear -- is it a determined policy for 
the language that it's not possible to return a tuple, or is it just something 
that has not yet been implemented?

Assuming it's language policy or just not going to arrive for some time, any 
advice on how to get a similar effect of returning multiple values?  I settled 
on defining a custom struct as return-type, but I'm not overly happy about it.

Thanks & best wishes,

     -- Joe

"Simen Kjaeraas" <simen.kjaras gmail.com> writes:

On Fri, 27 Apr 2012 14:52:08 +0200, Joseph Rushton Wakeling  
<joseph.wakeling webdrake.net> wrote:

 Hello all,

 Just recently I tried returning a Tuple from a function and received an  
 error message about this not being allowed.

 Reading up a bit on the D site I'm not clear -- is it a determined  
 policy for the language that it's not possible to return a tuple, or is  
 it just something that has not yet been implemented?

 Assuming it's language policy or just not going to arrive for some time,  
 any advice on how to get a similar effect of returning multiple values?   
 I settled on defining a custom struct as return-type, but I'm not overly  
 happy about it.


std.typecons has a type called Tuple, which is probably what you want:

import std.typecons;
Tuple!( int, string ) foo( ) {
     return tuple( 42, "Hello, world!" );
}

void bar( ) {
     auto a = foo( );
     assert( a[0] == 42 );
     assert( a[1] == "Hello, world!" );
}

There has been talk of making tuple support more built-in, but such has
not yet happened, and it is unclear when and if it will happen.

Oh, and there's more - Tuple supports named fields:

Tuple!( int, "amount", string, "color" ) baz( ) {
     // I thought this worked, but apparently not:
     //return tuple( 12, "red" );

     return typeof( return )( 12, "red" );
}

void qux() {
     auto b = baz( );
     assert( b.amount == 12 );
     assert( b.color = "red" );
}

Joseph Rushton Wakeling <joseph.wakeling webdrake.net> writes:

On 27/04/12 15:40, Simen Kjaeraas wrote:
 std.typecons has a type called Tuple, which is probably what you want:

... !

Can't believe I missed that.  Works perfectly, thanks so much! :-)