Tuple enhancement

[Dmitry Olshansky via Digitalmars-d]

On 10/16/16 3:58 PM, Andrei Alexandrescu wrote:
> I was thinking it would be handy if tuples had a way to access a field
> by name at runtime. E.g.:
>
> Tuple!(int, "a", double, "b") t;
> string x = condition ? "a" : "b";
> double v = t.get!string(x, 3.14);

I swear I've seen a pull request merged that adds an accessible "names" 
AliasSeq with names of fields. That should be a good starting point.

>
> The get method takes the field name and the type of the presumed field,
> and it returns the value of the field in the tuple. If no field by that
> name and type, return the second argument.
>
> Rquirements:
>
> * Do not throw - allow the second argument to be a throwing delegate
>
> * Do not add overhead if the method is never used
>
> * Figure out a reasonable (but not all too complicated) way to deal with
> implicit conversions, e.g. if x == "a" in the the code above, should it
> return 3.14 or convert the int to double?
>
> * Handle qualifiers appropriately
>
>
> Andrei
>