Two classes

Michael Mac

I've got a problem which I can't solve. I want to have 2 classes and both of them to have a pointer to each other...

public __gc class a
{
public:
a::a()
{
m_b->bb();
}

int aa()
{
    return 1;
}

private:
b* m_b;
};

public __gc class b
{
public:
b::b()
{
m_a->aa();
}
int bb()
{
return 1;
}
private:
a* m_a;
};

The code isn't able to compile. One solution is to use Object* instead of b* in the class a but I'll have to move my declaration to a cpp file and cast the pointer every time I want to use it. Mayby another solution? :confused: :confused: 43 68 65 65 72 73 2c 4d 69 63 68 61 65 6c

J Patel

Can't you forward declare class b? Jignesh

Maciej Pirog

Use __single_inheritance keyword! This is an example:

//Declarations:
public __gc class __single_inheritance b;
public __gc class a;
//Definitions:
public __gc class a
{
public:
a::a(){}
public:
b* m_b;
System::String* stringInClassA;
};

public __gc class b
{
public:
b::b(){}
public:
a* m_a;
System::String* stringInClassB;
};

// This is the entry point for this application
int _tmain(void)
{
a* A = new a();
b* B = new b();
A->stringInClassA = new String("This is string in class A");
B->stringInClassB = new String("This is string in class B");
A->m_b = B;
B->m_a = A;
Console::WriteLine(A->m_b->GetType()->ToString());
Console::WriteLine(B->m_a->GetType()->ToString());
Console::WriteLine("");
Console::WriteLine("from class A:");
Console::WriteLine(A->m_b->stringInClassB);
Console::WriteLine("");
Console::WriteLine("from class B:");
Console::WriteLine(B->m_a->stringInClassA);
int i = Console::Read ();

return 0;
}

The matrix has you :suss: MP Maciej Pirog

Michael Mac

Ok, but try to call a bb function on the m_b instance in the a class contructor. It won't compile. Any other tips? :cool: 43 68 65 65 72 73 2c 4d 69 63 68 61 65 6c

Michael Mac

It won't compile too because class b has a field m_a of class a. 43 68 65 65 72 73 2c 4d 69 63 68 61 65 6c

Maciej Pirog

Yoe'r right :-O But I've got an idea! Put: 1st classes declarations 2nd classes definitions and functions declarations 3rd functions definitions Example:

// Classes declarations:
public __gc class __single_inheritance b;
public __gc class __single_inheritance a;
// Classes definitions and functions *declarations*:
public __gc class a
{
public:
void AskClassBToWrite();
void WriteA();
b* m_b;
};

public __gc class b
{
public:
void AskClassAToWrite();
void WriteB();
a* m_a;
};
// functions *definitions*
void a::WriteA()
{
Console::Write("WriteA function was called");
}

void a::AskClassBToWrite()
{
a::m_b->WriteB();
}

void b::WriteB()
{
Console::Write("WriteB function was called");
}

void b::AskClassAToWrite()
{
b::m_a->WriteA();
}

// This is the entry point for this application
int _tmain(void)
{
a* A = new a();
b* B = new b();

A->m\_b = B;
B->m\_a = A;

A->AskClassBToWrite();
B->AskClassAToWrite();

Console::Read();
return 0;

}

This will work! :) MP Maciej Pirog

Michael Mac

Thanks man. It's working. :) :) :)

43 68 65 65 72 73 2c 4d 69 63 68 61 65 6c