calling a method without instantiating a class

[deevan]

Hello

I have a C++ Abstract class (NClass) of which a method f1 is being directly called. f1 is allocating memory (and its causing a memory leak).

Here's a representation of the code

class Nclass : public Zclass {
public:
	explicit Nclass();
	Nclass(const Nclass& a);
	virtual ~Nclass() {};

	virtual void f1(...); //this allocates memory for a rel and puts it on h_rel
	virtual bool f2(...)=0;
	
private:
	Heap<rel> h_rel;
};


Pclass::f1(...)
{
...
Nclass::f1();
...
}

My questions are:

1. How can Pclass::f1() directly call Nclass::f1 without instantiating an Nclass explicitly?
2. I set a breakpoint in gdb on Nclass::~Nclass and it was not hit - is that expected?
3. It looks like a new NClass is being generated each time Pclass::f1() is called (I set a breakpoint in gdb and saw that the "this pointer" changes. Where is the new NClass being deallocated.

thanks!

[ne555]

¿what is the relationship between Pclass and Nclass?

2. ¿did you destroy (implicit or explicit) any Nclass object?

[deevan]

Question #1 - thanks - that is likely a clue that I did not notice.

class Pclass : public Nclass
{
...
virtual void f1(...); // same signature as Nclass::f1
...
}

Pclass::f1(...)
{
...
Nclass::f1();
}

#2 - I didn't see any explicit or implicit call to delete Nclass.

[ne555]

¿how do you create the objects?

{
   Pclass *ptr = new Pclass; //bad
} //memory leak
{
   Pclass obj;
} //destructor call implicit 

1_ Pclass is an Nclass. Line 11 is calling the member function as defined in the parent class
3_ Nope, you are not creating another Nclass objects. As for this changing, show how did you measure that.

[deevan]

OK, thanks so much - its a bit convulated bit ultimately there is a new without a delete.
As for #3, this "creation of NClass" was just my bad understanding of some gdb output.