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Puppet_Sock wrote:

>> i try to write a class-function which can return two arguments by
>> reference.
> Don't. Re-factor your problem so that does not happen.
> Socks

I disagree, returning a small number of values (2, 3) in a struct is in
many cases an elegant solution and doesn't necessarily incur a
performance hit.

Quite a few times I have wished for C or C++ to have multiple return
values; if you've worked with them, you tend to miss them in languages
that don't have them.

Matthias Buelow <> wrote in news:62lo6lF23mqf3U1
@mid.dfncis.de:

> Puppet_Sock wrote:
>
>>> i try to write a class-function which can return two arguments by
>>> reference.
>> Don't. Re-factor your problem so that does not happen.
>> Socks
>
> I disagree, returning a small number of values (2, 3) in a struct is in
> many cases an elegant solution and doesn't necessarily incur a
> performance hit.
>
> Quite a few times I have wished for C or C++ to have multiple return
> values; if you've worked with them, you tend to miss them in languages
> that don't have them.
>

The OP might want to look at tr1::tuple() and tr1::tie(), They provide the
ability to return and assign multiple values at once. If tr1 isn't
available, then look at the boost libraries. They have implementations of
these.

joe

> I've tried the following:
>
> DataUnit returnValue = { m_someobject1,m_someobject2};
>
> but it doesnt work.


The following compiles just fine for me:

struct TwoIntRefs {
int &i, &j;
};

TwoIntRefs Func()
{
static int a = 55, b = 44;

TwoIntRefs const tir = {a,b};

return tir;
}

int main()
{
TwoIntRefs const tir = Func();

tir.i = 77;

tir.j = 33;
}

"Tomás Ó hÉilidhe" <> wrote in message
news:a73d7968-1705-4573-a23d-
...
> The following compiles just fine for me:
>
> struct TwoIntRefs {
> int &i, &j;
> };

There is also std:air<int&,int&>, although then you have to refer to
things as "first" and "second".

Lutz Altmann wrote:
>
> i try to write a class-function which can return two arguments by
> reference.
> My idea was to encapsulate the references in a struct :
>
> struct DataUnit
> {
> SomeClassType& m_object1;
> SomeOtherClassType& m_object2;
> };
>
> So that the function can return the two references by using the
> struct :
>
> DataUnit processSomething();
>
> My question is: How can i create the struct in the function ?
> I've tried the following:
>
> DataUnit returnValue = { m_someobject1,m_someobject2};
>
> but it doesnt work.
> ...

What exactly "doesn't work"?

--
Best regards,
Andrey Tarasevich

On 27 Feb., 18:17, "Eric.Malenf...@gmail.com"
<Eric.Malenf...@gmail.com> wrote:
> Lutz Altmann wrote:
> > hello,
>
> > i try to write a class-function which can return two arguments by
> > reference.
> > My idea was to encapsulate the references in a struct :
>
> > struct DataUnit
> > {
> > SomeClassType& m_object1;
> > SomeOtherClassType& m_object2;
> > };
>
> [snip]
>
> Boost.Tuple seems to fit nicely here :http://www.boost.org/libs/tuple/doc/...tml#constructi...
> Look at the make_tuple section and, in particular, to the use of ref()
> and cref().
>
> Non-tested example:
> class SomeClass
> {
> public:
> boost::tuple<SomeClassType&, SomeOtherClassType&> Foo()
> {
> return boost::make_tuple(boost::ref(m_SomeClass),
> boost::ref(m_SomeOtherClass));
> }
> private:
> SomeClassType m_SomeClass;
> SomeOtherClassType m_SomeOtherClass;
> };
>
> HTH,
>
> Éric Malenfant

nice,

for me it seems to be a very elegant solution.
i think i'll use this one or the template provided by the stl
std:air<int&,int&>

thanks a lot

On 27 Feb., 22:14, Andrey Tarasevich <andreytarasev...@hotmail.com>
wrote:
> Lutz Altmann wrote:
>
> > i try to write a class-function which can return two arguments by
> > reference.
> > My idea was to encapsulate the references in a struct :
>
> > struct DataUnit
> > {
> > SomeClassType& m_object1;
> > SomeOtherClassType& m_object2;
> > };
>
> > So that the function can return the two references by using the
> > struct :
>
> > DataUnit processSomething();
>
> > My question is: How can i create the struct in the function ?
> > I've tried the following:
>
> > DataUnit returnValue = { m_someobject1,m_someobject2};
>
> > but it doesnt work.
> > ...
>
> What exactly "doesn't work"?
>
> --
> Best regards,
> Andrey Tarasevich

sorry it was my fault - what i described at the beginning was not
really wrong ..
there was actually no problem with the code - blame on me

In message <>, Matthias Buelow
<> writes
>Puppet_Sock wrote:
>
>>> i try to write a class-function which can return two arguments by
>>> reference.
>> Don't. Re-factor your problem so that does not happen.
>> Socks
>
>I disagree, returning a small number of values (2, 3) in a struct is in
>many cases an elegant solution and doesn't necessarily incur a
>performance hit.

I think the objection is to returning references, not tuples.

>
>Quite a few times I have wished for C or C++ to have multiple return
>values; if you've worked with them, you tend to miss them in languages
>that don't have them.

--
Richard Herring