Don wrote:
Lars T. Kyllingstad wrote:
Denis Koroskin wrote:
On Thu, 29 Oct 2009 15:12:51 +0300, Lars T. Kyllingstad
<pub...@kyllingen.nospamnet> wrote:
Jason House wrote:
Andrei Alexandrescu Wrote:
It's a rough rough draft, but one for the full chapter on arrays,
associative arrays, and strings.
http://erdani.com/d/thermopylae.pdf
Any feedback is welcome. Thanks!
I still think is expressions are a glaring problem. Somewhere in
the text, you use assert(!is(typeof(... as support for what you're
talking about. That particular construct feels more like a hack
someone stumbled into than clean, easy to read code. It's the type
of thing a programmer will get wring unless they use it frequently.
Even you've screwed it up in past Phobos releases! IMHO all
is(...) expressions should be revisited. Have you written the
section(s) on them yet?
I don't think he uses is(typeof(...)) in the text. The code snippets
in question are marked "Note: normally the code below would not be
included...", and I suppose he's put them there as a reminder for
himself and Walter on what needs to be fixed before the book comes out.
I agree with you, though, is(typeof(...)) is quite often misused, or
at least used in an ugly way. Why not use __traits(compiles, ...)
instead?
-Lars
... which is at least as ugly.
I disagree. Pretend you are just learning D, and you are presented
with the following two lines of code:
static assert (is(typeof(XXX));
static assert (__traits(compiles, XXX));
Which of these would you most likely assume to be a check on whether
XXX is compilable code?
What I cannot for the life of me understand is WHY the double
underscores? What's wrong with just "traits"?
-Lars
Also is(typeof(XXX)) *doesn't* currently check that XXX is compilable,
just that it has a type.
OTOH __traits(compiles, XXX) is ugly. traits(compiles, XXX) would be
better; but I think we need to do better than that. It's the
bread-and-butter of metaprogramming in D. Using the ugly syntax, it has
well and truly proved its value.
I've counted 20 uses in what I've seen of Andrei's book -- it appears
about as often as (say) 'delegate'!
It does a beautiful thing, it deserves a beautiful syntax. Something at
least as good as __compiles(XXX), I reckon.
Again with the double underscores. :) I'm starting to think we need a
separate namespace for the CT stuff.
D.compiles(XXX)
D.typeof(foo)
D.stringof(T)
D.allMembers(T)
etc.
-Lars
