Tuple and tie?

[Meta via Digitalmars-d-learn]

On Tuesday, 8 July 2014 at 18:45:21 UTC, Remo wrote:
> On Tuesday, 8 July 2014 at 18:29:40 UTC, Meta wrote:
>> On Tuesday, 8 July 2014 at 17:42:00 UTC, Remo wrote:
>>>
>>> How to make something that work like std::tie in D2 ?
>>>
>>> Tuple!(float, float) sinCos(float n) {
>>> return tuple(cast(float)sin(n), cast(float)cos(n)); //please 
>>> note cast(float)!
>>> }
>>>
>>> int main(string[] argv) {
>>> float s,c;
>>> tie!(s,c) = sinCos(3.0f);
>>> }
>>
>> alias tie = TypeTuple;
>>
>> int main(string[] argv)
>> {
>>    float s,c;
>>    tie!(s,c) = sinCos(3.0f);
>> }
>
> Thanks !
> This is easier as I was thinking :)
> Now I only need to be sure that this do not have unwanted side 
> effects.

It's fine. There's not much to TypeTuple; it's defined like this:

alias TypeTuple(TList...) = alias TypeTuple = TList;

Where TList is any number of... things. Types, variables, values, 
template names, etc. Therefore, `TypeTuple!(s, c)` at a low level 
it's more or less like the following:

float s, c;

s = sinCos(3.0f)[0];
c = sinCos(3.0f)[1];

Not that sinCos is called twice. It's only called once, and the 
result is distributed across s and c.