CGAL::Modifier_base< R > Class Template Reference

#include <CGAL/Modifier_base.h>

Definition

Modifier_base is an abstract base class providing the interface for any modifier.

A modifier is a function object derived from Modifier_base that implements the pure virtual member function operator(), which accepts a single reference parameter R& on which the modifier is allowed to work. R is the type of the internal representation that is to be modified.

Example

The following fragment defines a class A with an internal representation i of type int. It provides a member function delegate(), which gives a modifier access to the internal variable and checks validity thereafter. The example modifier sets the internal variable to 42. The example function applies the modifier to an instance of class A.

class A { 
  int i; // protected internal representation 
public: 
  void delegate( CGAL::Modifier_base<int>& modifier) { 
    modifier(i); 
    CGAL_postcondition( i > 0); // check validity 
  } 
}; 

struct Modifier : public CGAL::Modifier_base<int> { 
  void operator()( int& rep) { rep = 42;} 
}; 

void use_it() { 
  A a; 
  Modifier m; 
  a.delegate(m); // a.i == 42 and A has checked that A::i > 0. 
} 

Types
typedef R	Representation
	the internal representation type.

Operations
virtual void	operator() (R &rep)

Member Function Documentation

template<typename R>

virtual void CGAL::Modifier_base< R >::operator() ( R &  rep)

virtual

Postcondition

rep is a valid representation.