This is Simple query related to Factory Design Pattern... Have a look at the
Auto Registration of Factory Design pattern..
:)
Prem
On Fri, Sep 23, 2011 at 3:02 PM, algo geek <geeka...@gmail.com> wrote:
> You have a library provided by the vendor. All you have is header files and
> library files.
> Library contains the class Shape and there is whole hierarchy tree (i mean
> classes which derive from this base class).
> Now you want to add some function "getArea" (not originally present in the
> class or any of its derived class) in the class "Shape" , you dont have the
> source code.
>
> Using this library, you have written a lot of code. Now you have to make
> some changes so that, any object of Shape class (or its derived class) will
> be able to call this function.
> With your strategy, you should be able to override the definition of this
> function in the derived class.
>
> I think it is related to design patterns, not sure.
> I gave the solution that : we will use MyShape , and use composition. i.e.
> will create the object of Shape class inside this "NewShape" class and
> interface can be made. Internally, we can call the functions of "Shape"
> object. That will work fine. But we have to do this for the whole design
> hierarchy. Secondly, if there is some changes by the vendor in future in the
> library, i have to change my new design tree.
> e.g.
> class Shape {
> public : void draw();
> void clear();
> }
> class Circle : public Shape{
> public : void draw();
> void clear();
> }
> class Rectangle: public Shape{
> public : void draw();
> void clear();
> }
>
>
> class NewShape{
> private Shape * obj;
> public : void draw(){ obj->draw(); }
> void clear() { obj->clear(); }
> int getArear(){
> //implementtation of getArea function
> }
> }
>
> class NewCircle : NewShape{
> public : void draw(){ (Circle*)obj->draw(); }
> void clear() { (Circle*)obj->clear(); }
> int getArear(){
> //implementtation of getArea function specific to
> circle
> }
> }
> class NewRectangle : NewShape{
> public : void draw(){ (Rectangle*)obj->draw(); }
> void clear() { (Rctangle*)obj->clear(); }
> int getArear(){
> //implementtation of getArea function
> }
> }
>
> I know this solution is not good.. please provide a better approach for
> this.
> Please let me knw if anything is not clear.
>
>
>
>
> Thanks in advance.
>
> --
> You received this message because you are subscribed to the Google Groups
> "Algorithm Geeks" group.
> To post to this group, send email to algogeeks@googlegroups.com.
> To unsubscribe from this group, send email to
> algogeeks+unsubscr...@googlegroups.com.
> For more options, visit this group at
> http://groups.google.com/group/algogeeks?hl=en.
>
--
You received this message because you are subscribed to the Google Groups
"Algorithm Geeks" group.
To post to this group, send email to algogeeks@googlegroups.com.
To unsubscribe from this group, send email to
algogeeks+unsubscr...@googlegroups.com.
For more options, visit this group at
http://groups.google.com/group/algogeeks?hl=en.
