C++ guys hate static_if?

[monarch_dodra]

On Saturday, 9 March 2013 at 14:09:39 UTC, Andrei Alexandrescu 
wrote:
> On 3/8/13 7:48 PM, DypthroposTheImposter wrote:
>> See the static_if paper here:
>>
>> http://isocpp.org/forums
>>
>> Under the post "constraints and static if" there is a link to a
>> document about
>> static_if
>>
>> https://docs.google.com/viewer?a=v&pid=forums&srcid=MDIyMDc3NjUwMTczOTM0Mjk3NjABMDI2MzM3MjkxNDM4NDQ5MzE4NDcBLWVsS1Y4dFhtdDhKATUBaXNvY3BwLm9yZwF2Mg
>>
>>
>> Are they full of it? Has it caused the problems they mention
>> in
>> D?
>
> Wow. That's quite out of character for Bjarne. I think it's 
> quite a poor piece.
>
> Andrei

I think there is a bit of forced bashing in there, but the main 
point is that static if prevents eager semantic validation of 
templated code. In C++, if you write a semantically incorrect 
template, then the compiler can catch it. This is not possible 
once static ifs enter the picture.

I know for a fact I've had the C++ compiler catch a fair amount 
of errors for me, whereas it takes actual intantiation for the D 
compiler to catch said errors (and I've seen a few such errors in 
phobos).

I think the main point is not "is static if good or not": I think 
D has clearly demonstrated how powerful it can be. However, to 
the question of "is it the right move for C++, whith all of its 
heritage, to adopt static if?" As a C++ developper, honestly, I'm 
not sure it is. I think that's where the piece is comming from, 
in maybe a clumsy manner.

C++ took a different road with its "horrible" template syntax, 
but it took that road. I think it is better to improve that road 
(with concepts, for example), then try to move the current 
paradigm.

That's might point of view having mostly a "full C++" background, 
and having learned D. The bottom line, I think, is that it is an 
error to think of D as "just" improved C++, and that what might 
work for D might not be what is best for C++. It doesn't mean 
that static if (or other D constructs) are bad in and out of 
themselves. I wouldn't take this piece as a "direct attack" on D.

...

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.