A Tuple is a an aggregate of typed values. Tuples are useful for returning
a set of values from a function or for passing a set of parameters to a
function.
NOTE:
Since the transition from user-defined to built-in tuples, the ability
to return tuples from a function has been lost. Until this issue is
addressed within the language, tuples must be enclosed in a struct
if they are to be returned from a function.
Example:
alias Tuple!(int, real) T1;
alias Tuple!(int, long) T2;
struct Wrap( Vals... )
{
Vals val;
}
Wrap!(T2) func( T1 val )
{
Wrap!(T2) ret;
ret.val[0] = val[0];
ret.val[1] = val[0] * cast(long) val[1];
return ret;
}
This is the original tuple example, and demonstates what should be possible
with tuples. Hopefully, language support will be added for this feature
soon.
Example:
alias Tuple!(int, real) T1;
alias Tuple!(int, long) T2;
T2 func( T1 val )
{
T2 ret;
ret[0] = val[0];
ret[1] = val[0] * cast(long) val[1];
return ret;
}
// tuples may be composed
alias Tuple!(int) IntTuple;
alias Tuple!(IntTuple, long) RetTuple;
// tuples are equivalent to a set of function parameters of the same type
RetTuple t = func( 1, 2.3 );