Calling a parents function from a child class?

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_Pauli_

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Joined: 13th Aug 2009

Location: Germany

Posted: 20th May 2010 18:58

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This is more like C++ question than DarkGDK but I guess it fits here anyway.

So how do I call a function of a parent class from one of its childrens classes?

Example:

The child class:

+ Code Snippet

class cChild
{
public:
   void ChildFunction();
};

Now the parent class:

+ Code Snippet

class cParent
{
public:
   void FunctionA();

   cChild ChildA,
          ChildB;
}
ParentA;

So let's say I want to call ParentA.FunctionA() from within ChildA.ChildFunction().

1) How would I do this?

2) Is it possible to call ChildB.ChildFunction() from ChildA.ChildFunction()?

Thanks in advance!

Now the plot thickens, the fps decreases, and the awesomeness goes through the roof.

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Ultimate_H

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Joined: 11th Mar 2009

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Posted: 20th May 2010 19:26

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I believe I posted some code that did just this kind of think earlier. Basically, you define the ChildFunction() after the parent object has been created (ie: cParent p). so it would look something like this:

+ Code Snippet

class Child
{
public:
     void childFunction();
};

class Parent
{
     Child chi;
public:
     void ParentFunction();
};

Parent p;

void Child::childFunction()
{
     p.ParentFunction();
}

this hasn't been tested in the case of the child being owned by the parent, but has been tested where the calling class is above the called class.

Hope that's what your looking for
-H

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_Pauli_

AGK Developer

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Posted: 20th May 2010 19:40

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Ok, thanks.
Unfortunatly that's not exactly what I'm looking for...

Of course the Child (in your example) can access p.ParentFunction() since it has been created before in the global scope.

In my case, the child doesn't "know" about its parent, except that it was created from it. Sounds strange, not sure if that is even possible in C++...

Now the plot thickens, the fps decreases, and the awesomeness goes through the roof.

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JTK

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Joined: 10th Feb 2010

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Posted: 20th May 2010 20:32

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Have the Child hold a pointer to the parent; ie:

+ Code Snippet

class cParent; /* forward declaration */

class cChild
{
public:
   void ChildFunction();
   void SetParent(cParent *p) {
     if (NULL != p)
       m_Parent = p;
   }

protected:
  cParent *m_Parent;

};

class cParent
{
public:
   cParent(void) {  /* constructor */
     ChildA.SetParent(this);
     ChildB.SetParent(this);
   } 
   void FunctionA();

   cChild ChildA,
          ChildB;
}
ParentA;

Then your child class can access m_Parent->FunctionA() just as you need...

JTK

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_Pauli_

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Posted: 20th May 2010 22:21

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Ah cool, thanks!
I thought about something along those lines...
I'm going to try it later.

By the way, is protected the same as private?

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JTK

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Posted: 20th May 2010 22:28

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Not quite. private is private. Mine. No-one else even knows about it; protected is a little bit more relaxed in that it's mine, but if you inherit from me, I'll share with you...

JTK

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Dark GDK / Calling a parents function from a child class?