On Friday, 13 September 2013 at 15:16:36 UTC, H. S. Teoh wrote:
On Fri, Sep 13, 2013 at 04:16:30PM +0200, simendsjo wrote:
On Friday, 13 September 2013 at 14:02:15 UTC, Gary Willoughby
wrote:
[...]
>A lot of the traits stuff is very confusing, i think a lot of
>it
>is still being finalised and in development. I'm working on a
>project using a lot of traits stuff and it's doing my head
>in. I
>wish there was better documentation. e.g. what is 'func' in
>the
>code above? i'm using it successfully but i've no idea what
>it is.
I know what you mean. Have been using quite some __traits and
is(),
and I still have to look up the syntax for is() all the time,
and
experiment with both trying to find the edge-cases.
[...]
The syntax for is() is one gigantic mess. It does work, but
it's not
pretty. IIRC Walter admitted that it could do with some
cleanup, but
it's a bit too late now since too much code relies on its
quirks.
As for __traits, I believe the intention was that it wasn't
meant for
end-user consumption, but for Phobos to be able to access
compiler
internals. As such, it only provides the bare minimum for
Phobos to be
able to work, so there are a lot of quirks and edge cases. I
was quite
dismayed yesterday to discover that "parameter type tuples" are
actually
different from the usual "type tuples", and don't even behave
consistently with foreach (they masquerade as type tuples w.r.t.
foreach, and there's weird special-casing for 1-element slices
of them,
e.g. for __traits(identifier...)). I don't know what's the
rationale for
this strange design, but it sure looks like it was just a quick
hack to
make Phobos work rather than anything carefully thought out.
Personally, I would just stick with the Phobos interfaces, and
file bugs
(or pull requests) if the existing interfaces aren't sufficient
for your
needs.
T
We should clean up this mess in 'is' and 'traits' and especially
for tuples. IMO it's ok if it breaks code as long as it helps to
write cleaner and tough code. This will also help D to gain more
attention.
There is so many crap in D... We should really start to clean up
as long as D2 is still a Beta.
And we should stop to transform it into something like C++ with
transferring built-in features into the library (like scope or
delete).
