Potential delete from stack

[RichardF]

Hi,

The title makes it sound bad. I'll explain by example.
Sorry about the volume of code, but its simple.

template <class A>
class Pointer {
public:
Pointer()tr(NULL) {};
Pointer() { if (ptr) delete ptr; };

void Add(T *pValue) {
ptr = pValue;
}

void Add(T &Value) {
Add(&Value);
}

private:
T* ptr;
};


class RF {
public:
RF():Age(0) {};
void SetAge(int Value) { Age = Value };
private:
int Age;
};


int main() {
RF Sue;

Sue.SetAge(21);

Pointer<RF> *P = new Pointer<RF>;

P->Add(Sue);

// .... do something

delete P;

return 0;
}

Finally, the question is. When I call delete P, which calls the Pointer destructor to delete ptr - do i have to distingush between variables that come from the stack or the heap ? will Sue be deleted twice ?

Thanks in advance.

Rich.

 

[palbano]

void Add(T &Value) {
Add(&Value);
}

BAD... VERY BAD

You should get a copy of Myers &quot;More Effective C++&quot; or whatever the latest version is.

If you add a destructor to your template that deletes &quot;ptr&quot; it will blow chunks.

I don't know what your trying to do exactly, what you posted is ok since your template class has no destructor defined the deletes &quot;ptr&quot;.

Perhaps you could explain your goal.

-pete

 

[RichardF]

Hi Pete,

Sorry this line:

Pointer() { if (ptr) delete ptr; };

should have read :

~Pointer() { if (ptr) delete ptr; };

All that aside, that was just an example that illustrates what i was trying to do. I didnt want to post reams of the real thing.

This explains why it blows up when the program completes. I understand now.

Thanks.

 

[palbano]

Rich, sounds like you have a handle now, but yeah you can't delete stack based memory only heap based allocations.

-pete