forward declaration of a structure nested in a class

[Stephane Routelous]

Hi,

I would like to make a forward declaration of a strcuture nested in a class.
I have

file A.h
class A
{
public:
struct B
{
};
};

file C.h
class C
{
public:
static doIt(const A::B& object);
};

I tried :
struct A::B;
but it doesn't work ( MSVCPP 6.0 last SP )

Is it a way to do that ?

thanks in advance,

Stephane Routelous

[John Carson]

"Stephane Routelous" <no****@nowhere .com> wrote in message
news:c1******** **@dns3.cae.ca

Hi,

I would like to make a forward declaration of a strcuture nested in a
class. I have

file A.h
class A
{
public:
struct B
{
};
};

file C.h
class C
{
public:
static doIt(const A::B& object);
};

I tried :
struct A::B;
but it doesn't work ( MSVCPP 6.0 last SP )

Is it a way to do that ?

No, the only type of forward declaration allowed for a nested class is one
inside the enclosing class, e.g.,

class Outer
{
// forward declaration of inner class
class Inner;
// other stuff
}

// full declaration of inner class
class Outer::Inner
{
// Inner stuff
};
--
John Carson
1. To reply to email address, remove donald
2. Don't reply to email address (post here instead)

[Gianni Mariani]

Stephane Routelous wrote:

Hi,

I would like to make a forward declaration of a strcuture nested in a class.
I have

file A.h
class A
{
public:
struct B
{
};
};

file C.h
class C
{
public:
static doIt(const A::B& object);
};

I tried :
struct A::B;
but it doesn't work ( MSVCPP 6.0 last SP )

Is it a way to do that ?

No.

You might be able to use a template, i.e.:

class A;

class C
{
public:
template <class tA>
static int doIt(const typename tA::B & object);
};
class A
{
public:
struct B
{
};
};
template <>
int C::doIt<A>(cons t A::B & object)
{
}
oops now I'm not sure you can specialize outside of the class
declaration - this one is new to me.

[Gianni Mariani]

Gianni Mariani wrote:

Stephane Routelous wrote:

.... Sorry I'd suggest you do it this way below - that way you don't need
to specify the <A> in doit<A>.
class A;

class C
{
public:
template <class tA_B>
static int doIt(const tA_B & object);
};
class A
{
public:
struct B
{
};
};
template <>
int C::doIt<A::B>(c onst A::B & object)
{
return 0;
}
int main()
{
A::B x;

C::doIt( x );
}


oops now I'm not sure you can specialize outside of the class
declaration - this one is new to me.

I'm still not sure this is legal but g++ (3.4prerel) works fine with it.

[Stephane Routelous]

I tried that, but I got a beautiful internal compiler error with vc++6.0

Thanks,

Stephane

"Gianni Mariani" <gi*******@mari ani.ws> wrote in message
news:c1******** @dispatch.conce ntric.net...

Gianni Mariani wrote:

Stephane Routelous wrote:

... Sorry I'd suggest you do it this way below - that way you don't need
to specify the <A> in doit<A>.
class A;

class C
{
public:
template <class tA_B>
static int doIt(const tA_B & object);
};
class A
{
public:
struct B
{
};
};
template <>
int C::doIt<A::B>(c onst A::B & object)
{
return 0;
}
int main()
{
A::B x;

C::doIt( x );
}

>
> oops now I'm not sure you can specialize outside of the class
> declaration - this one is new to me.
>

I'm still not sure this is legal but g++ (3.4prerel) works fine with it.

[Gianni Mariani]

Stephane Routelous wrote:

I tried that, but I got a beautiful internal compiler error with vc++6.0

vc++6.0 is too old. Time to upgrade to GCC ... :-)