comp.std.c++ Google Group

Re: Is it safe to cast std::array::data() to built-in array reference?

2009-12-04T08:35:01Z

Anders Dalvander replied:
Thanks, but does it work for a non-empty std::array? Is it safe to convert
the pointer returned by std::array<T,N>::data() to a reference of type
T(&)[N], when N > 0? Aren't there any possible alignment issues that might
make such a reference useless?
Kind regards,
Niels

Re: Lambda captures in N2960

2009-12-03T18:02:24Z

Now wait a second.
(defparameter x 42)
(+ x x) ;; yields 84 here
(lambda (x) (+ x x)) ;; here stuck in a lambda, still 84?
Well, no, not when you introduce a new 'x' which
hides the other one.
;; how about this
(defmacro screw-with-environment (&forms)
`(let ((x -1)) ,@forms))

Re: Is N2479 going into C++0x?

2009-12-03T18:02:26Z

N2479 was looked at on 2008-02-28 by the LWG and was not forwarded to
full committee for a vote into the WP.
-Howard

Re: Implementation of array

2009-12-03T18:01:30Z

Since it's not mentioned by others yet, I guess It's helpful to add
this link by Herb Sutter:
[link]
On 12月1日, 上午2时21分, "Johannes Schaub (litb)" <schaub-johan...@web.de>
wrote:

Re: accumulate algorithm

2009-12-03T18:01:28Z

As "Bo Persson" states:
"the intention is to accumulate the values into the parameter".

Re: Lambda captures in N2960

2009-12-03T07:04:01Z

Now wait a second.
(defparameter x 42)
(+ x x) ;; yields 84 here
(lambda (x)
(+ x x)) ;; here stuck in a lambda, still 84?
;; how about this
(defmacro screw-with-environment (&forms)
`(let ((x -1)) ,@forms))
(screw-with-environment (+ x x)) ;; still 84?
If you stick a body of code somewhere where the references which emanate from

Re: Lambda captures in N2960

2009-12-03T04:30:40Z

Someone already pointed out why this should be - when you
take a block of code and stick it into a lambda, you should
not change its semantics.
void f(const int &) { } // #1
void f( int &) { } // #2
void g() {
int const x;
f(x); // Calls #1
auto l = [=] mutable { f(x); };

Re: Is it safe to cast std::array::data() to built-in array reference?

2009-12-03T04:24:43Z

On Dec 1, 11:38 pm, "Niels Dekker - no reply address"
It may not work if N == 0.
Regards,
Anders Dalvander

Re: Lambda captures in N2960

2009-12-03T04:27:51Z

Re: Implementation of array

2009-12-03T04:22:27Z

I think i could have been clearer with my wording. What i meant is that you
end up having one implementation defined partial specialization with "<T,
0>" and one you write yourself with "<int, N>". Then a reference to type
"foo<int, 0>" is ambiguous.
In your code, you had an additional explicit specialization for "<int, 0>",

Is N2479 going into C++0x?

2009-12-03T04:24:18Z

Hi,
Can anyone tell if N2479 changes will be available in C++0x?
Regards,
&rzej

Re: Lambda captures in N2960

2009-12-03T04:27:34Z

std::parallel?

2009-12-03T04:22:23Z

Given high level parallel task libraries like Intel TBB, STAPL, Cilk+
+, VC++ PPL, OpenMP (with current explicit task constructs), & also
given C++’s system of standardizing existing widespread practice, is
it too early to tell which of these libraries will form a base of a
future C++ standard parallel library?

Is it safe to cast std::array::data() to built-in array reference?

2009-12-01T22:38:12Z

Can someone please tell me if the following function,
user_namespace::get_c_array, is guaranteed to get a valid reference to a
built-in array from a non-empty C++0x std::array?
namespace user_namespace
{
template <typename T, std::size_t N>
T(& get_c_array(std::array<T,N>& arg) )[N]
{
return *static_cast<T(*)[N]>(

Re: Implementation of array

2009-12-01T22:36:49Z

On 1 Dez., 06:53, Daniel Kr=FCgler <daniel.krueg...@googlemail.co m>
wrote:
happen?
a
The
I think my previous conclusion was incorrect and as currently
specified their is no requirement for a partial specialization.
Nevertheless such an implementation technique seems conforming
to me and my suggestion to prevent possible ambiguities is to