I have function which have more than one return, and the code compile and run but it gives rong result -I guess-, so i use tuple but the compiler can't return tuple.

how can I return values?
why I can't return tuple?

%u:

> I have function which have more than one return, and the code compile and run but it gives rong result -I guess-, so i use tuple but the compiler can't return tuple.
> 
> how can I return values?
> why I can't return tuple?

Currently in D there are two ways to return multiple values from a function:
- To use a std.typecons.tuple (not a std.typetuple).
- To use "out" function arguments.

Regarding typetuples, they can't be used to return multiple values from a function because of differences in stack alignment, this means incompatible ABI of D functions and D typetuples. This is not a great thing, but I presume that doing otherwise breaks a "zero overhead" constraint Walter seems to require to D typetuples.

Given the presence of typecons tuples (and maybe in future some syntax sugar to use them in a more handy way), this is not a significant limitation. It's mostly strange to have two very different kinds of tuples in a single language.

Bye,
bearophile

On 2011-04-20 01:35:46 +0300, %u said:

> I have function which have more than one return, and the code compile and run
> but it gives rong result -I guess-, so i use tuple but the compiler can't
> return tuple.
> 
> how can I return values?
> why I can't return tuple?

In D, tuple is not built in type, it is defined in stantard library. To use it, you must import module std.typecons

Example:
import std.typecons;
 
struct Foo {}
 
Tuple!(int, string, Foo) baz() {
    // some computation here
    return tuple(13, "inches", Foo());
}
 
void main() {
    auto bar = baz();
    assert(bar == tuple(13, "inches", Foo()));
}

thanks you all, it works.

last thing, I have this
Tuple!(int,int,int)(1, 2, 3)

how can I use the return values individual?

to be more clear if I rturn tuple(a, b, c) can I write in the code

void main() {

//call the function here
writeln(a);

}

%u:

> how can I use the return values individual?

One of the simpler ways is to think of a tuple as an array, and use sometuple[0] to take its first item, etc. But your tuple indexes need to be compile-time constants.

Bye,
bearophile