Uzytkownik "Greg Herlihy" <greghe@pacbell.net> napisal w wiadomosci
news:1165409202.575999.37530@n67g2000cwd.googlegroups.com...
>
> John Nagle wrote:
>> This is valid, but requires typedefs.
>> Can this return type be written in a single statement?
>> Or does that exceed the capabilities of the declaration syntax?
>>
>> typedef char array3[3];
>> typedef array3& array3ref;
>>
>> array3ref foo();
>
> I'm not sure whether a valid declaration ever requires a typedef -

operator char (&(void))[02], anyone?
Chris


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This is valid, but requires typedefs.
Can this return type be written in a single statement?
Or does that exceed the capabilities of the declaration syntax?

 typedef char array3[3];
 typedef array3& array3ref;

 array3ref foo();


    John Nagle
    Animats

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John Nagle wrote:
> This is valid, but requires typedefs.
> Can this return type be written in a single statement?
> Or does that exceed the capabilities of the declaration syntax?
>
>  typedef char array3[3];
>  typedef array3& array3ref;
>
>  array3ref foo();

I'm not sure whether a valid declaration ever requires a typedef -
though they can certainly help. I believe in this case the equivalent
declaration without resorting to a typedef would be:

    char ( &foo() )[3];

Greg

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"John Nagle" <nagle@animats.com> wrote in message
news:pvpdh.19462$9v5.10796@newssvr29.news.prodigy.net...

> This is valid, but requires typedefs.
> Can this return type be written in a single statement?
> Or does that exceed the capabilities of the declaration syntax?

> typedef char array3[3];
> typedef array3& array3ref;

> array3ref foo();

charr (&foo())[3];

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On Dec 6, 2:38 pm, John Nagle <n...@animats.com> wrote:
> This is valid, but requires typedefs.
> Can this return type be written in a single statement?
> Or does that exceed the capabilities of the declaration syntax?
>
>         typedef char array3[3];
>         typedef array3& array3ref;
>
>         array3ref foo();
>
You can do it as follow:
typedef char (&array3ref)[3];

But I don't think this type is useful ^_^  , array3& is enough

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John Nagle wrote:
> This is valid, but requires typedefs.
> Can this return type be written in a single statement?
> Or does that exceed the capabilities of the declaration syntax?
>
>     typedef char array3[3];
>     typedef array3& array3ref;
>
>     array3ref foo();

Looks nothing special to me, beyond the usual pathological
nature of C++ declaration syntax:

char array[3];

char (&foo())[3]
{
  return array;
}

This compiles for me with Comeau C++ 4.3.3, and with g++
3.3.  (Of course it's clearer with suitable typedefs, and
this is rather an odd case to want anyway, but the syntax
allows it.)

-- James

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John Nagle wrote:
> This is valid, but requires typedefs.
> Can this return type be written in a single statement?
> Or does that exceed the capabilities of the declaration syntax?

>  typedef char array3[3];
>  typedef array3& array3ref;

>  array3ref foo();

    char (&foo())[ 3 ] ;

As usual, you start with what you want to declare: "foo".  It's
a function, so "foo()", which returns a reference "&foo()" to
an array "&foo()[3]"---but the precedance is wrong, so we need
parentheses "(&foo())[3]".  And finally, char.

I'll admit that it looks a little strange as a definition:

    char (&foo())[ 3 ]
    {
        //  ...
    }

Make it a const member function, and have the array contain
pointers to member functions, and the syntax can become
downright difficult.  Something like the following (which
declares a function taking an int as a parameter, and not a
double):

    void (Bar::*(&Bar::foo( int i ) const)[ 3 ])( double d )

(To read, at least.  Curiously, I find it easier to write the
declarations.  But what good is it to write such declarations,
if you don't understand what they mean when you later read the
code?)

--
James Kanze (GABI Software)             email:james.kanze@gmail.com
Conseils en informatique orient   e objet/
                   Beratung in objektorientierter Datenverarbeitung
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