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From: Alex Strickland on 24 Feb 2010 15:29
Seungbeom Kim wrote:
> I should align the text when the 'for' statement goes multiple lines:
>
> for (std::map<std::string, int>::const_iterator i = member_ages.begin();
> i != member_ages.end(); ++i) {
> // body
> }
>
> No matter how I did it, it wasn't satisfactory. :(

I always use a second tab to further indent the second (or third) part of lines
that are too long.

Alex

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From: Chris M. Thomasson on 24 Feb 2010 15:26
"Hakusa(a)gmail.com" <hakusa(a)gmail.com> wrote in message
news:bfdcc972-7f40-451c-9c57-d6e7b6d088d9(a)z35g2000yqd.googlegroups.com...
> Firstly, this seems like something there'd already be a topic about,
> but i didn't see it. Also, i'm not sure if this is the right place to
> ask, but...
>
> What C++0x features are most relevant to you?
[...]

That would have to be:
__________________________________________
std::thread
std::mutex
std::condition_variable
std::atomic<T>
__________________________________________

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From: Klaus Rudolph on 25 Feb 2010 15:56
Hakusa(a)gmail.com schrieb:

>
> What C++0x features are most relevant to you?

* lambdas!
* delegating constructors.
* unique initializer lists for all data types

I think the actual upcoming standard looks more straightforward. A lot
things become much clearer.

But one of the new disadvantages: lambda pointers could only be used in
templates and the type is 'unknown'. I have not found a reason for that
behavior. Maybe this will be corrected in the next release :-) A generic
functor could be used as workaround. But this not as cool as it could be .


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From: Hakusa on 25 Feb 2010 15:57
On Feb 24, 7:24 am, SG <s.gesem...(a)gmail.com> wrote:
> On 24 Feb., 01:18, "Hak...(a)gmail.com" <hak...(a)gmail.com> wrote:

> > On Feb 23, 3:00 pm, SG <s.gesem...(a)gmail.com> wrote:
> > > On 23 Feb., 03:51, "Hak...(a)gmail.com" <hak...(a)gmail.com> wrote:
> > > > [...]
> > > But rvalue references would not help you in such cases (unless the
> > > array's elements can be moved much faster than copied). Rvalue
> > > references are great in case "logical members" are heap-allocated and
> > > only referenced through a pointer member (see std::vector, for
> > > example).
>
> > The way i use rvalue references is in the operator+ function:
>
> > // Pseudo code
> > template< T1, T2, S >
> > Vector<T2,S>&& operator+( const Vector<T1,S>& a, Vector<T2,S>&& b )
> > {
> > b += a;
> > return std::move(b);
> > }
>
> > Rather than creating a vector with a+b, then another with (a+b)+c, it
> > should create a temporary with a+b, then add c onto (a+b), then copy
> > that into d.
>
> You mean a+(b+c), right? Only the 2nd parameter of this operator+
> function is an rvalue reference.

Implicitly, there's a function where the rvalue ref is on the other
side. Sorry about that; i considered writing both, but thought one was
enough.

> Anyhow, I'd consider it unsafe and it
> is likely not worth the hassle of writing this overload. I would guess
> that this doesn't safe any significant amount of time (Have you
> measured it?).

No. I wrote that it is of interest to me, and i haven't measured
anything yet, but without it being interesting to me, and without
writing the function, i couldn't find out. Besides, i didn't start
this thread to talk about my usage, but my and other's interest, and
using rvalue references for this kind of operation was introduced to
me by the VC++ blog; i just happen to find the concept cool.

> It's unsafe because it allows you to write things like
>
> auto const& foo = a + (b + c);

> The current draft N3035 still contains some operator+ functions for
> strings which return rvalue references. But my understanding is that
> this is going to be replaced. See LWG issue #1138:http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2010/n3018.html#1138

Interesting you note that! What introduced me to the idea of using
rvalue references for this purpose is reading about just this use of
them on the VC++ blog. I guess it makes sense; even if i think using
auto with any kind of zeal is bad, reserving it for cases where there
is much more ambiguity than here, i can see how that creates a more
fool-proof program... Thank you for bringing my attention to that!


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From: Florian Weimer on 25 Feb 2010 16:35
* Mathias Gaunard:

F> On Feb 24, 12:18 am, "Hak...(a)gmail.com" <hak...(a)gmail.com> wrote:
>
>> The way i use rvalue references is in the operator+ function:
>>
>> // Pseudo code
>> template< T1, T2, S >
>> Vector<T2,S>&& operator+( const Vector<T1,S>& a, Vector<T2,S>&& b )
>> {
>> b += a;
>> return std::move(b);
>>
>> }
>
> This realize this modifies its right operand, which isn't something
> operator+ should do?
> Did you mean to only apply that to non-lvalues?

AFAIK, && only binds to rvalues, not lvalues anymore. Apparently,
N2844 was adopted into the draft standard.

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