typedef, Typedef

[Andrei Alexandrescu]

On 11/23/13 12:55 PM, bearophile wrote:
> But both workarounds are bad when you have many items, a long name for
> the typedef, or your T is the type of the keys or values of an
> associative array.
>
> Can this situation be fixed/improved?

Typedef!T is meant as a type with the same behavior as T, but otherwise 
unrelated to it. The code above suggests it behaves as advertised. 
Allowing uncontrolled conversions to and fro is only making typedef 
weaker. Asking for features just because "they worked with typedef" is 
unlikely to fare well because typedef was just a weird artifact with 
arbitrary semantics that were nice half the time and darn surprising the 
other half.

We could add a flag such that Typedef!(T, supertype) that allows T as a 
supertype, i.e. add an alias this. There is no possibility to add 
implicit construction of Typedef!T from T (and that's arguably a good 
thing).


Andrei