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Qt-interest Archive, December 2007
[OT] QPainterPath overloading operator =

Message 1 in thread

Hi all

I know this is not a Qt issue, but I'm in doubt on how to overload the
equal operator for a QPainterPath-derived class.

My class just add an index to the QPainterPath... but how can I make
the contents of the base class equal ?

Here was my first attempt:

XPlanePath& XPlanePath::operator=(const XPlanePath& _path)

{
   if (&_path == this) return *this;

   index = _path.index;

//  *((QPainterPath*)this) = *((QPainterPath*)_path);  <---- ERROR

   return *this;
}

thanks in advance

    Andy

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Message 2 in thread

Andy Hirsh wrote:
>//  *((QPainterPath*)this) = *((QPainterPath*)_path);  <---- ERROR

QPainterPath::operator=(_path);

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Message 3 in thread

On Saturday 01 December 2007 09:49:21 Andy Hirsh wrote:
> Hi all
>
> I know this is not a Qt issue, but I'm in doubt on how to overload the
> equal operator for a QPainterPath-derived class.
>
> My class just add an index to the QPainterPath... but how can I make
> the contents of the base class equal ?

Just call the operator= from the parent:

E.g,

#include <iostream>

using namespace std;

struct A {
   int m_a;
   const A& operator=(const A& rhs) { m_a = rhs.m_a; return *this; }
 };

struct B : public A {
   int m_b;
   const B& operator=(const B& rhs) {
        A::operator=(rhs);
        m_b = rhs.m_b;
        return *this;
   }
 };

int main() {
        B one;
        B two;
        one.m_a = 1;
        one.m_b = 2;
        two.m_a = 3;
        two.m_b = 4;

        two = one;

        cout << "two.m_a=" << two.m_a << endl;

}



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