## Projection_object

### Definition

The concept Projection_object is modeled after the STL concept UnaryFunction, but takes also care of (const) references.

Projection_object::argument_type
| argument type.
Projection_object::result_type
| result type.

### Creation

Projection_object o;
| default constructor.

### Operations

result_type& | o.operator() ( argument_type &) const
const result_type& | o.operator() ( const argument_type &) const

### Has Models

CGAL::Identity<Value>
CGAL::Dereference<Value>
CGAL::Get_address<Value>
CGAL::Cast_function_object<Arg, Result>
CGAL::Project_vertex<Node>
CGAL::Project_facet<Node>
CGAL::Project_point<Node>
CGAL::Project_normal<Node>
CGAL::Project_plane<Node>
CGAL::Project_next<Node>
CGAL::Project_prev<Node>
CGAL::Project_next_opposite<Node>
CGAL::Project_opposite_prev<Node>