On Sat, 13 Nov 2010 16:09:32 -0500, spir <denis.s...@gmail.com> wrote:
On Sat, 13 Nov 2010 13:19:25 -0500
bearophile <bearophileh...@lycos.com> wrote:
Steven Schveighoffer:
> Then you just wasted time duping that argument. Instead of a
defensive
> dup, what if we had a function ensureHeaped (better name suggestions?)
I have created a bug report to avoid this whole pair of threads to be
lost in the dusts of time:
http://d.puremagic.com/issues/show_bug.cgi?id=5212
Feel free to add a note about your ensureHeaped() idea at the end of
that enhancement request :-)
(To that enhancement request I have not added my idea of the @onheap
attribute because I think it's too much complex to implement according
to the design style of the D compiler).
Bye,
bearophile
I was the one bitten by the bug. I think it's really a naughty feature,
was about to create a bug entry when saw Bearophile's post. In my
opinion, if
void f(int[] ints) {doWhateverWith(ints);}
works, then
void f(int[] ints...) {doWhateverWith(ints);}
must just work as well.
I don't really agree. The ... version is optimized so you can pass
typesafe variadic args. If the compiler would generate a heap allocation
for that, then you may be wasting a lot of heap allocations. One thing
you may learn in D is that heap allocation == crappy performance. The
less you allocate the faster your code gets. It's one of the main reasons
Tango is so damned fast. To have the language continually working against
that goal is going to great for inexperienced programmers but hell for
people trying to squeeze performance out of it.
I think what we need however, is a way to specify intentions inside the
function. If you intend to escape this data, then the runtime/compiler
should make it easy to avoid re-duping something.
I consider variadic args as just syntactic honey for clients of a func,
type, lib. There should be no visible semantic difference, even less
bugs (and certainly not segfault when the code does not manually play
with memory!). But I may have wrong expectations about this feature in
D, due to how variadics work in other languages I have used.
It was hard to debug even with the help of 3 experienced D programmers.
To be fair, it was easy to spot when you gave us the pertinent code :)
-Steve
