C++ guys hate static_if?

[Andrei Alexandrescu]

On 3/14/13 1:37 PM, deadalnix wrote:
> On Thursday, 14 March 2013 at 17:07:16 UTC, Andrei Alexandrescu wrote:
>> Very simple. Traditionally there's two crucial epochs known as
>> compilation time and run time. (There's some minor distinctions like
>> link time etc.) The whole notion of concepts and other type systems
>> for templates is predicated on three crucial epochs: library
>> compilation time, library user compilation time, and run time. The
>> logic goes, someone writes a generic library and wants to distribute
>> it to users. Users shouldn't ever see bugs caused by e.g. typos in the
>> library.
>>
>
> I'm not sure if you are thinking I'm really stupid here.

Being wrong doesn't make one stupid.

>> So the crowd that use meta-type systems is formed of library writers
>> who want to distribute libraries without ever instantiating them. I
>> don't think that's a good crowd to cater for.
>>
>> I've been surprised to figure how many people don't get this flow, or
>> only have a vague image of it. Although meta-types are arguably "the
>> right thing" to do, they're a lot less attractive once it's clear what
>> scenarios they help.
>>
>
> Let me demonstrate with an actual example :
[snip]
> Yes I added the bar on purpose in some heavily templated code. You
> concentrate too much on theses people that want to ship code without
> using it. They'll do it anyway.
>
> And that make even more sense from the lib user perspective, as having
> the compiler vomit kilometers of internals of a lib is usually not
> helpful (this happen a lot with phobos).

Template constraints are D's solution to that issue. I agree it's not 
perfect, but I think dollar for dollar it's better than concepts.

Andrei