Re: How do I make this into a hierachy

John Grabner wrote:


See http://en.wikipedia.org/wiki/Composite_pattern

If I understand you correctly, you may be interested in the Composite
Pattern.

//Defines your interface
struct Base
{
  virtual void print() = 0; //perhaps const
};

class Leaf_HierarchA : public Base
{
  //Implements print ...
};

class Leaf_HierachB : public Base
{
  //Implements print...
};

class Composite : public Base
{
  public:
    void add( Base& );
    void remove( Base& );
    virtual void print()
    {
      //for each item in leaves_, call print...
    }
  private:
    std::list<Base*> leaves_;
};

One does get variations on this implementation, such as making Base
concrete - assuming all leaves will have the possibility of being
composite:

struct Base
{
  public:
    //...Constructors etc...
    void add( Base& );
    void remove( Base& );
    void print()
    {
      //For each leave, call doPrint.
    }
  private:
    virtual void doPrint() = 0; //perhaps const - default may throw...
    
    std::list<Base*> leaves_;
};

Cheers,

W

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