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hello all,

how can i make, a forward declaration class's enum member, being
visible by another class?

consider the following case,

----------------------------
dog.h
----------------------------
#ifndef DOG_H
#define DOG_H

// class forward declaration.
class cat;

class dog
{
public:
enum dog_enum
{
d0, d1, d2
};

void speak(cat *c);
};

#endif

----------------------------
cat.h
----------------------------
#ifndef CAT_H
#define CAT_H

#include "dog.h"

class cat
{
public:
void speak(dog *d, dog::dog_enum e);
};

#endif

The above cat and dog just work fine. Now, let me create an enum type
for cat too.

----------------------------
dog.h
----------------------------
#ifndef DOG_H
#define DOG_H

// class forward declaration.
class cat;

class dog
{
public:
enum dog_enum
{
d0, d1, d2
};

// OPPS! HOW DO WE FORWARD DECLARE ENUM???
void speak(cat *c, cat::cat_enum e);
};

#endif

----------------------------
cat.h
----------------------------
#ifndef CAT_H
#define CAT_H

#include "dog.h"

class cat
{
public:
enum cat_enum
{
c0, c1, c2
};

void speak(dog *d, dog::dog_enum e);
};

#endif

My question is, how can "dog" see the cat_enum, which is re-inside cat?
I was understand that forward declaration for enum is not allowed in
c++.

Is there any workaround for this?

Thank you very much

wrote:
> how can i make, a forward declaration class's enum member, being
> visible by another class?
>
> consider the following case,
>
> ----------------------------
> dog.h
> ----------------------------
> #ifndef DOG_H
> #define DOG_H
>
> // class forward declaration.
> class cat;
>
> class dog
> {
> public:
> enum dog_enum
> {
> d0, d1, d2
> };
>
> void speak(cat *c);
> };
>
> #endif
>
> ----------------------------
> cat.h
> ----------------------------
> #ifndef CAT_H
> #define CAT_H
>
> #include "dog.h"
>
> class cat
> {
> public:
> void speak(dog *d, dog::dog_enum e);
> };
>
> #endif
>
> The above cat and dog just work fine. Now, let me create an enum type
> for cat too.
>
> ----------------------------
> dog.h
> ----------------------------
> #ifndef DOG_H
> #define DOG_H
>
> // class forward declaration.
> class cat;
>
> class dog
> {
> public:
> enum dog_enum
> {
> d0, d1, d2
> };
>
> // OPPS! HOW DO WE FORWARD DECLARE ENUM???
> void speak(cat *c, cat::cat_enum e);
> };
>
> #endif
>
> ----------------------------
> cat.h
> ----------------------------
> #ifndef CAT_H
> #define CAT_H
>
> #include "dog.h"
>
> class cat
> {
> public:
> enum cat_enum
> {
> c0, c1, c2
> };
>
> void speak(dog *d, dog::dog_enum e);
> };
>
> #endif
>
> My question is, how can "dog" see the cat_enum, which is re-inside cat?
> I was understand that forward declaration for enum is not allowed in
> c++.
>
> Is there any workaround for this?

Yes: pull the enum outside the class, putting it in the same namespace
as its associated class. Then in cat.h, you can do:

namespace Canine
{
enum dog_enum;
class dog;
}

class cat
{
// ...
void MewAt( Canine::dog*, Canine::dog_enum );
};

and in dog.h, you can do:

namespace Feline
{
enum cat_enum;
class cat;
}

class dog
{
// ...
void BarkAt( Feline::cat*, Feline::cat_enum );
};

Cheers! --M

mlimber wrote:
> Yes: pull the enum outside the class, putting it in the same namespace
> as its associated class. Then in cat.h, you can do:
>
> namespace Canine
> {
> enum dog_enum;
> class dog;
> }
>

namespace Feline // Forgot this... sorry
{
enum cat_enum { c1, c2 };
> class cat
> {
> // ...
> void MewAt( Canine::dog*, Canine::dog_enum );
> };

}

>
> and in dog.h, you can do:
>
> namespace Feline
> {
> enum cat_enum;
> class cat;
> }
>

namespace Canine
{
enum dog_enum { d1, d2 };
> class dog
> {
> // ...
> void BarkAt( Feline::cat*, Feline::cat_enum );
> };

}

Cheers! --M

wrote:

> My question is, how can "dog" see the cat_enum, which is re-inside cat?
> I was understand that forward declaration for enum is not allowed in
> c++.
>
> Is there any workaround for this?
>
Declare the enums separately from the classes. Use a namespace
if you like.