On Saturday, 9 March 2013 at 15:22:55 UTC, monarch_dodra wrote:
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.
The more I think of it, the more this whole duck typing for
templates is probably a bad solution because we lack tool to
express « meta types ».
