sigc::adapts< T_functor > Struct Template Reference

Base type for adaptors. More...

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

Inheritance diagram for sigc::adapts< T_functor >:

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

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

Detailed Description

template <typename 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 adaptor_type alias 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 <typename T_functor>
struct my_adaptor : public sigc::adapts<T_functor>
{
  //
  decltype(auto)
  operator()() const;
  //
  template <typename T_arg1>
  decltype(auto)
  operator()(T_arg1 arg1) const;
  //
  template <typename T_arg1, typename T_arg2>
  decltype(auto)
  operator()(T_arg1 arg1, T_arg2 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& functor)
    : sigc::adapts<T_functor>(functor) {}
};
} // end namespace my_ns
//
// Specialization of sigc::visitor for my_adaptor.
namespace sigc
{
template <typename T_functor>
struct visitor<my_ns::my_adaptor<T_functor> >
{
  template <typename T_action>
  static void do_visit_each(const T_action& action,
                            const my_ns::my_adaptor<T_functor>& target)
  {
    sigc::visit_each(action, 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.

Constructor & Destructor Documentation

adapts()

template <typename T_functor >

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

inlineexplicit

Constructs an adaptor that wraps the passed functor.

Parameters

functor

Functor to invoke from operator()().

Member Data Documentation

functor_

template <typename T_functor >

adaptor_type sigc::adapts< T_functor >::functor_

mutable

Adaptor that is invoked from operator()().