sigc::adapts< T_functor > Struct Template Reference

Base type for adaptors. More...

#include <sigc++/adaptors/adaptor_trait.h>

Inheritance diagram for sigc::adapts< T_functor >:

Public Types
typedef adaptor_trait< T_functor >::adaptor_type	adaptor_type
typedef adaptor_trait< T_functor >::result_type	result_type

Public Member Functions
	adapts (const T_functor & _A_functor)
	Constructs an adaptor that wraps the passed functor. More...

Public Attributes
adaptor_type	functor_
	Adaptor that is invoked from operator()(). More...

Detailed Description

template<class T_functor>
struct sigc::adapts< T_functor >

Base type for adaptors.

sigc::adapts wraps adaptors, functors, function pointers and class methods. It contains a single member functor which is always a sigc::adaptor_base. The typedef adaptor_type defines the exact type that is used to store the adaptor, functor, function pointer or class method passed into the constructor. It differs from T_functor unless T_functor inherits from sigc::adaptor_base.

Example of a simple adaptor:

namespace my_ns
{
template <class T_functor>
struct my_adaptor : public sigc::adapts<T_functor>
{
  template <class T_arg1=void, class T_arg2=void>
  struct deduce_result_type
  { typedef sigc::deduce_result_t<T_functor, T_arg1, T_arg2> type; };
  typedef typename sigc::functor_trait<T_functor>::result_type result_type;
  //
  result_type
  operator()() const;
  //
  template <class T_arg1>
  typename deduce_result_type<T_arg1>::type
  operator()(T_arg1 _A_arg1) const;
  //
  template <class T_arg1, class T_arg2>
  typename deduce_result_type<T_arg1, T_arg2>::type
  operator()(T_arg1 _A_arg1, T_arg2 _A_arg2) const;
  //
  // Constructs a my_adaptor object that wraps the passed functor.
  // Initializes adapts<T_functor>::functor_, which is invoked from operator()().
  explicit my_adaptor(const T_functor& _A_functor)
    : sigc::adapts<T_functor>(_A_functor) {}
};
} // end namespace my_ns
//
// Specialization of sigc::visitor for my_adaptor.
namespace sigc
{
template <class T_functor>
struct visitor<my_ns::my_adaptor<T_functor> >
{
  template <class T_action>
  static void do_visit_each(const T_action& _A_action,
                            const my_ns::my_adaptor<T_functor>& _A_target)
  {
    sigc::visit_each(_A_action, _A_target.functor_);
  }
};
} // end namespace sigc

If you implement your own adaptor, you must also provide your specialization of sigc::visitor<>::do_visit_each<>() that will forward the call to the functor(s) your adapter is wrapping. Otherwise, pointers stored within the functor won't be invalidated when a sigc::trackable object is destroyed and you can end up executing callbacks on destroyed objects.

Your specialization of sigc::visitor<> must be in namespace sigc.

Member Typedef Documentation

adaptor_type

template <class T_functor >

typedef adaptor_trait<T_functor>::adaptor_type sigc::adapts< T_functor >::adaptor_type

result_type

template <class T_functor >

typedef adaptor_trait<T_functor>::result_type sigc::adapts< T_functor >::result_type

Constructor & Destructor Documentation

adapts()

template <class T_functor >

sigc::adapts< T_functor >::adapts ( const T_functor &  _A_functor )

inlineexplicit

Constructs an adaptor that wraps the passed functor.

Parameters

_A_functor

Functor to invoke from operator()().

Member Data Documentation

functor_

template <class T_functor >

adaptor_type sigc::adapts< T_functor >::functor_

mutable

Adaptor that is invoked from operator()().