Article on Tuples

[Bruno Medeiros]

Walter Bright wrote:
> Don Clugston wrote:
>> One problem -- it seems that if the tuple has a mix of types and 
>> instances, you can't index it.
>> -------------
>> struct S { int x; long y; }
>>
>> template Tuple(E...)
>> {
>>     alias E Tuple;
>> }
>>
>> void main()
>> {
>>     int q;
>>
>>     alias Tuple!(S, q) Z;
>>     alias Z[0] R; // fails -- "tuple E is used as a type"
>> }
>> -------------
> 
> About the only thing you can do with mixed tuples is pass them as 
> arguments to another template.
> 
>> Also, is there any way to get .tupleof to return an alias tuple?
>> For example, you can't write
>> alias S.tupleof[0] R;
> 
> That's because you can't have an alias to an expression. You can have a 
> pointer to an expression, though:
> 
>     auto R = &S.tupleof[0];
> 

Indexed Tuples are only expressions in syntax, not such much 
conceptually. What if we could also index tuple elements using template 
instantiation:
    alias S.tupleof!(0) R;
Then perhaps the aliasing would work with the current compiler/language 
rules.

-- 
Bruno Medeiros - MSc in CS/E student
http://www.prowiki.org/wiki4d/wiki.cgi?BrunoMedeiros#D