Inheritance declaration

[jan247]

my header file looks like this:

class A;
class B;
class C;

class A
{
....
};

class Bublic A
{
private:
B doSomething(A& a);
public:
B processMe(C c){...; doSomething(c);} // Problematic statment
};

class C: public A
{
....
}

The problem is that by the time it reaches the line of code with the
problematic statement, it hasn't declared yet that C indeed extends A.
Is there any way on how I can declare this? Or any other possible
options if i can't?

 

[Ivan Vecerina]

: my header file looks like this:
:
: class A;
: class B;
: class C;
:
: class A
: {
: ....
: };
:
: class Bublic A
: {
: private:
: B doSomething(A& a);
: public:
: B processMe(C c){...; doSomething(c);} // Problematic statment
: };
:
: class C: public A
: {
: ....
: }
:
: The problem is that by the time it reaches the line of code with the
: problematic statement, it hasn't declared yet that C indeed extends A.
: Is there any way on how I can declare this? Or any other possible
: options if i can't?

You have to provide the definition(=implementation)
of processMe after class C has been seen, for example:

class Bublic A
{
private:
B doSomething(A& a);
public:
B processMe(C c); // (forward-)declaration
};

class C: public A
{
....
};

B A:rocessMe(C c) {...; doSomething(c);} // definition



(you could use reinterpret_cast, but this would formally be UB)


Ivan

 

[jan247]

: my header file looks like this:
:
: class A;
: class B;
: class C;
:
: class A
: {
: ....
: };
:
: class Bublic A
: {
: private:
: B doSomething(A& a);
: public:
: B processMe(C c){...; doSomething(c);} // Problematic statment
: };
:
: class C: public A
: {
: ....
: }
:
: The problem is that by the time it reaches the line of code with the
: problematic statement, it hasn't declared yet that C indeed extends A.
: Is there any way on how I can declare this? Or any other possible
: options if i can't?

You have to provide the definition(=implementation)
of processMe after class C has been seen, for example:

class Bublic A
{
private:
B doSomething(A& a);
public:
B processMe(C c); // (forward-)declaration
};

class C: public A
{
....
};

B A:rocessMe(C c) {...; doSomething(c);} // definition



(you could use reinterpret_cast, but this would formally be UB)


Ivan

Ahhh.. thanx!

 

[red floyd]

my header file looks like this:

class A;
class B;
class C;

class A
{
....
};

class Bublic A
{
private:
B doSomething(A& a);
public:
B processMe(C c){...; doSomething(c);} // Problematic statment
};

class C: public A
{
....
}

The problem is that by the time it reaches the line of code with the
problematic statement, it hasn't declared yet that C indeed extends A.
Is there any way on how I can declare this? Or any other possible
options if i can't?

Is there a particular reason that you're passing C by value rather than
by const reference? If you use a reference, you can do this:

class C;

class B : public a
{
///
public:
B processMe(const C&);
};


Also, separate the declaration and defintion of B:rocessMe().