pgplot::Handle< X > Class Template Reference

The handle class. More...

#include <pghandle.h>

Inheritance diagram for pgplot::Handle< X >:

Collaboration diagram for pgplot::Handle< X >:

Public Types
Typedefs for class template Handle.
Note typedef const X* Tpointer_to_const; is not the same as typedef const Tpointer Tpointer_to_const;
typedef X	Tvalue
typedef X *	Tpointer
typedef X &	Treference
typedef const X *	Tpointer_to_const
typedef const X &	Treference_to_const
typedef HandleOfConst< Tvalue >	Tbase
typedef Handle< Tvalue >	Tcontainer
typedef Tbase	Tcontainer_of_const
typedef Tcontainer_of_const	Tcoc

Public Member Functions
template<class Y >
Tcontainer &	operator= (const Handle< Y > &h)
	Assignement operator providing transparency to inheritance. More...
Constructors
Action is provided by base class.
	Handle ()
	Default constructor. More...
	Handle (Treference_to_const x)
	Initializing constructor. More...
template<class Y >
	Handle (const Handle< Y > &h)
	Copy constructor providing transparency to inheritance. More...
Write access operators.
Tpointer	operator-> () const
	Write access operator with pointer semantics. More...
Treference	operator* () const
	Write access operator with pointer semantics. More...

Protected Member Functions
Write access operators must be protected
Tpointer	pointer () const
	expose the pointer to derived classes More...
Treference	reference () const
	expose the object to derived classes More...

Detailed Description

template<class X>
class pgplot::Handle< X >

The handle class.

This handle class provides transparency to class inheritance. Consider a base class A

class A {
...
};

and a derived class B

class B: public A {
  public:
    // constructor
    B(const int& i, const int& j);
...
};

where the contstructor is just an example to illustrate code below. If you want to provide access to the same instance of B at more than one locations within your code, it is safe to use a Handle<B> that can be initialized in a straight forward way like

Handle<B> b(B(3,4));

The value b can be passed around safely, providing access to the contained value of type B with pointer semantics. No consider a function

void sample(const Handle<A>& a);

that accepts a handle to the base class you can simply call this function by

sample(b);

and the contents of the object of type B will be available within function sample through virtual functions.

See also

Example code is available in pgtestxx.cc

Therein example code is available in functions testhandle() and testhandlefunction()

Definition at line 219 of file pghandle.h.

---

The documentation for this class was generated from the following file:

• pghandle.h