• Gor Gyolchanyan (23/23) Oct 01 2011 I wonder why aren't tuples fully supported in D?
• Timon Gehr (9/32) Oct 01 2011 This interferes with the comma operator. A, B; will evaluate A and then

Gor Gyolchanyan <gor.f.gyolchanyan gmail.com> writes:

I wonder why aren't tuples fully supported in D?

string, int, float createTuple()
{
    return "hello", 5, 6.7f;
}

unittest
{
    string s;
    int i;
    float f;

    s, i, f = createTuple();
}

Wouldn't this be a cleaner way of dealing with static-length
heterogeneous collections of variables?
The comma operator would have a single definite meaning: creating a
tuple out of left-hand variable or tuple and right-hand variable.
The existing use of comma wouldn't change:
* All functions will technically take 1 argument only: a variable or a tuple.
* Comma-separated expressions are technically a single tuple expression.
* UFCS will get expanded to include tuples: ("/", "usr",
"bin").buildNormalizedPath;

It's easy to imagine the same thing but with support for tuples
consisting of any symbols, and nut just variables.

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

On 10/01/2011 12:17 PM, Gor Gyolchanyan wrote:
 I wonder why aren't tuples fully supported in D?

 string, int, float createTuple()
 {
      return "hello", 5, 6.7f;
 }

 unittest
 {
      string s;
      int i;
      float f;

      s, i, f = createTuple();
 }

 Wouldn't this be a cleaner way of dealing with static-length
 heterogeneous collections of variables?
 The comma operator would have a single definite meaning: creating a
 tuple out of left-hand variable or tuple and right-hand variable.
 The existing use of comma wouldn't change:
 * All functions will technically take 1 argument only: a variable or a tuple.
 * Comma-separated expressions are technically a single tuple expression.
 * UFCS will get expanded to include tuples: ("/", "usr",
 "bin").buildNormalizedPath;

 It's easy to imagine the same thing but with support for tuples
 consisting of any symbols, and nut just variables.

This interferes with the comma operator. A, B; will evaluate A and then 
B and the result of the expression is the result of B. I agree that 
built-in tuples would be really nice. Unfortunately, making them nice 
would amount to a breaking change. There is a nice pull request by Kenji 
Hara that would allow this:

auto (a,b,c) = createTuple();

For an appropriate definition of createTuple (function returning library 
tuple/range/...)