C++ guys hate static_if?

[monarch_dodra]

On Saturday, 9 March 2013 at 16:05:59 UTC, Andrei Alexandrescu 
wrote:
> On 3/9/13 10:22 AM, monarch_dodra wrote:
>> BTW, in regards to template constraints (not the rest), he 
>> does have a
>> point. We have raised the exact same issues here on the boards 
>> more than
>> once.
>
> What was the problem for D again?
>
> Andrei

"Problem" is a big word. But basically, the combination: "if your 
template type doesn't meet template constraints, where did it 
fail?" We don't have that, but concepts do. This is part of the:
- Should we use constraints only for overloads or also to 
validate types?
- Should we instead use static asserts to find out why the 
argument type is wrong?

  That said, concepts (afaik) don't handle overloads...

...which brings us to managing said overloads. Basically, right 
now, if you want overloads, you have to repeat the conditions in 
a:

if (a && !b)
...
if (b && !c)
...
if (c)

This is minor, but it does not scale very well, especially if 
"a", "b" and "c" are complicated. In algorithm, some of our 
constraints for sort/find can be 5 lines long. At this point, can 
we still say that they are readable tools for users, or an 
implementation tool for dispatch?

Things can get evenmore hairy,when you are operating on 2 
different types.

One last thing to keep in mind is that having constraints allows 
hijacking, whereas concpets/static asserts resolve as an ambigus 
call.

----
Not a breaking issue or anything, just more of an anoyance. I 
wanted to point out that we ourselves have already had talks 
about the points raised in said article.

Regardless, that was not the main point that I was trying to get 
accross. My main point was simply that what works for D might not 
be best for C++.