On Friday, 24 July 2015 at 23:13:25 UTC, deadalnix wrote:
On Friday, 24 July 2015 at 19:56:55 UTC, Shammah Chancellor
wrote:
I put up a PR for phobos awhile ago for concepts as a library
to kind of start the discussion around concepts. There
seemed to be some interest around the PR, so I have rebased it
and fixed the formatting.
Please take a look:
https://github.com/D-Programming-Language/phobos/pull/2627
-Shammah
Doing it as a library would miss a lot of the point of concepts
:
- Compiler can do a fair amount of semantic analysis on
template before instantiating them. This work is done once
rather than repeating it a every template instantiation.
- It allow for much more clearer error messages. Anyone having
to maintain some meta code will understand what I'm talking
about here.
- It make compile time and runtime polymorphism more alike. I
do think we'd all agree that Andrei approach to mention
template arguments as compile time arguments and go from there
is a good move. Concept would be the same move, but for typing.
By reusing common language constructs (C++ failed to use that
opportunity) for instance.
Agreed, that's why I left the PR alone for so long before someone
pinged me on it. I sort of did it as a POC and didn't quite end
up liking the results. The library solution would be okay if it
was easier to get diagnostics -- but currently that requires
nasty hacks if you looked at the docs.
