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Re: C++ puzzle - how to get this to compile ?

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On 12/2/2011 1:28 AM, Juha Nieminen wrote:
> OSS542<jhart666@gmail.com>  wrote:
>> class cls2
>> {
>>     friend void cls1::fun1();
>> };
>> class cls1
>> {
>>         cls2 mbr1;
>>     public:
>>         void fun1();
>> };
>
>    In principle there's no technical reason why that couldn't be done. It's
> just a question of lacking syntax in the language.
>
>    It would be useful if one could, somehow, declare member functions before
> the class definition is known. (If the class then fails to define the
> declared member function, a linker error would happen.) This can be done
> with namespaces, but not with classes.
>
>    I'd say a syntax like this would be enough:
>
> class A;
> int A::foo(int, int);
>
>    Anyone see any problem with that?

I think you're advocating forward-declaration of member functions.  In 
that case the full qualification should be allowed for forward-declaring 
static, virtual, default, pure virtual and const members of the class. 
Basically there shouldn't be a problem if you want to write

     virtual int A::foo(int,int) const = 0;

outside the class itself.  However, currently the grammar does not allow 
the keyword 'virtual' to be used outside a class definition, and also 
defines a different meaning of the keyword 'static'.

I don't see "any problem" except that the grammar needs to be made even 
more complicated to allow out-of-the-class-definition member declarations.

V
-- 
I do not respond to top-posted replies, please don't ask

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C++ puzzle - how to get this to compile ? OSS542 <jhart666@gmail.com> - 2011-11-30 16:24 -0800
  Re: C++ puzzle - how to get this to compile ? Bart v Ingen Schenau <bart@ingen.ddns.info> - 2011-12-01 13:54 +0100
    Re: C++ puzzle - how to get this to compile ? OSS542 <jhart666@gmail.com> - 2011-12-06 13:08 -0800
  Re: C++ puzzle - how to get this to compile ? Paavo Helde <myfirstname@osa.pri.ee> - 2011-12-01 11:34 -0600
    Re: C++ puzzle - how to get this to compile ? Victor Bazarov <v.bazarov@comcast.invalid> - 2011-12-01 13:52 -0500
      Re: C++ puzzle - how to get this to compile ? Victor Bazarov <v.bazarov@comcast.invalid> - 2011-12-01 13:53 -0500
      Re: C++ puzzle - how to get this to compile ? Paavo Helde <myfirstname@osa.pri.ee> - 2011-12-01 16:03 -0600
  Re: C++ puzzle - how to get this to compile ? Juha Nieminen <nospam@thanks.invalid> - 2011-12-02 06:28 +0000
    Re: C++ puzzle - how to get this to compile ? Victor Bazarov <v.bazarov@comcast.invalid> - 2011-12-02 11:12 -0500
      Re: C++ puzzle - how to get this to compile ? Juha Nieminen <nospam@thanks.invalid> - 2011-12-02 16:36 +0000

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