Argumnentation against external function operator overloading is unconvincing

[HaraldZealot via Digitalmars-d]

On Thursday, 22 September 2016 at 07:14:52 UTC, H. S. Teoh wrote:
>
> It's not so simple.  The UFCS operator overload could be 
> declared in a different module from the type itself.  Then 
> there is no guarantee that it will be found.  Multiple calls to 
> the same template function with the same argument types may 
> result in different semantics, depending on what was imported.
> ...
> T

I mean (in terms of your example) that in `main` before 
instantiate an `algorithm` we parse all symbols visible at this 
point from `main`, select all possible symbols which can be 
called with `UserType` (including templates, meh o_O), make the 
set union for the such table for the rest templates params, and 
give this symbol table the `algorithm`.

But yes this creates problem that in different module we can have 
different instantiation :(

Probably with other radical approach (see bellow *) for generic 
we can solve this, but this just destroy true templates (from 
which we benefits now) and provide something like Java-like 
solution :(

* radical approach for generic: each generic function creates a 
pseudo parameter for function pointers on the base of signature 
of function used in the body of generic. The caller of generic 
just fill this pseudo parameters with real function visible for 
caller at call-point.