Tuple enhancement

[sarn via Digitalmars-d]

On Sunday, 16 October 2016 at 13:58:51 UTC, 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);
>
> 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

Personally, if I wanted this, I'd be using a hash table with 
Variant objects in it or something.  An argument for keeping 
tuple features simple is that they really aren't a good tool for 
doing anything fancy.  If you need a runtime interface, you're 
probably outgrowing tuples already.  Why not make a struct that 
contains a hash table?