Thread: How to redefine a constructor from parent class

Hello guys.
Firstly I don't really know if this is possible.

This is my Class Diagram:
https://dl.dropboxusercontent.com/u/...0diagramV4.png

github:
https://github.com/CreativeSoftware/DiamondQTv3

I want to redefine the price object of the Book Class.
However price is defined at Products Class.

I want the price value change according to the marker value, which is a Book attribute.
If the marker is blue, price gets a value of 10 (e.g.), if it has another value, price is equal to 20.

Also posted here.

Jim

Originally Posted by jimblumberg

Also posted here.

Jim

Yes, I post in both places, without answers
Thanks !

Originally Posted by laserlight

I do not see what is so difficult that you have to wait 10 hours for an answer on two forums when an hour or less of thinking should have led you to an answer to try.

Looking at your class diagrams: the price member is protected and there is a public member function to change it. Therefore, you have two ways of setting the price in a Book class constructor.

I'm learning C++, last years I used procedural languages (fortran, C) and Matlab. Everything is difficult until I know how to do.

I'll use your "miyagi tip" to try to figure out how it works.
I've tried first. I spend 2 hours after posting. To me it is not easy chaging programming paradigms, it's a different way of think.

Originally Posted by marcoesteves

I'm learning C++, last years I used procedural languages (fortran, C) and Matlab. Everything is difficult until I know how to do.

I'll use your "miyagi tip" to try to figure out how it works.
I've tried first. I spend 2 hours after posting. To me it is not easy chaging programming paradigms, it's a different way of think.

I think that I got it.

Code:

Book l1("1231", "title", "nice Author", "Nice Publisher", 1, "blue", 1021, 10);

l1.setPrice(100);

string str1 = "blue";

     if (str1.compare(l1.marker()) == 0)
     {  cout << "the marker is blue" << "\n";
         l1.setPrice(200);
     }
     else
         l1.setPrice(400);

Hey OP, is this what you were trying to go for?

Code:

#include <iostream>


class A
{
    private :


        int x;


    public :
    
        A( void )
        {
            x = -1;
            std::cout << "A's constructor ( " << x << " )\n";
        };


        A( int y )
        {
            x = y;
            std::cout << "New x : " << x << "\n";
        };
};


class B : public A
{


    public :


        B( void )
        {
            std::cout << "B's constructor\n";
        }
};


int main( void )
{
    B test;
    B::A( 15 );


    return 0;
}

Yeah, I figured the only way to change a private variable would be to do it that way. Otherwise, I think you need the member variable you're trying to change as public. I figure you could just redefine B::B to change the price assuming it's public. If it's not, then I don't think there's any to change it except by calling the class directly.

Oh sorry, I thought this problem was about changing the price value in the Product class using the Book constructor. I admit, my example was off XD

I think I'll just slink back into the shadows. I didn't really read the topic that well.