sigc::trackable_signal< T_return(T_arg...)>::accumulated< T_accumulator > Class Template Reference

Like sigc::trackable_signal but the additional template parameter T_accumulator defines the accumulator type that should be used. More...

#include <sigc++/signal.h>

Inheritance diagram for sigc::trackable_signal< T_return(T_arg...)>::accumulated< T_accumulator >:

Public Member Functions
	accumulated ()=default
	accumulated (const accumulated & src)
Public Member Functions inherited from sigc::trackable_signal_with_accumulator< T_return, T_accumulator, T_arg... >
	trackable_signal_with_accumulator ()=default
	trackable_signal_with_accumulator (const trackable_signal_with_accumulator & src)
	trackable_signal_with_accumulator (trackable_signal_with_accumulator && src)
connection	connect (const slot_type & slot_)
	Add a slot at the end of the list of slots. More...
connection	connect (slot_type && slot_)
	Add a slot at the end of the list of slots. More...
connection	connect_first (const slot_type & slot_)
	Add a slot at the beginning of the list of slots. More...
connection	connect_first (slot_type && slot_)
	Add a slot at the beginning of the list of slots. More...
decltype(auto)	emit (type_trait_take_t< T_arg >... a) const
	Triggers the emission of the signal. More...
decltype(auto)	make_slot () const
	Creates a functor that calls emit() on this signal. More...
decltype(auto)	operator() (type_trait_take_t< T_arg >... a) const
	Triggers the emission of the signal (see emit()). More...
trackable_signal_with_accumulator &	operator= (const trackable_signal_with_accumulator & src)
trackable_signal_with_accumulator &	operator= (trackable_signal_with_accumulator && src)
Public Member Functions inherited from sigc::signal_base
	signal_base () noexcept
	signal_base (const signal_base & src) noexcept
	signal_base (signal_base && src)
	~signal_base ()
void	block (bool should_block=true) noexcept
	Sets the blocking state of all slots in the list. More...
bool	blocked () const noexcept
	Returns whether all slots in the list are blocked. More...
void	clear ()
	Empties the list of slots. More...
bool	empty () const noexcept
	Returns whether the list of slots is empty. More...
signal_base &	operator= (const signal_base & src)
signal_base &	operator= (signal_base && src)
size_type	size () const noexcept
	Returns the number of slots in the list. More...
void	unblock () noexcept
	Unsets the blocking state of all slots in the list. More...
Public Member Functions inherited from sigc::trackable
	trackable () noexcept
	trackable (const trackable & src) noexcept
	trackable (trackable && src) noexcept
	~trackable ()
void	add_destroy_notify_callback (notifiable *data, func_destroy_notify func) const
	Add a callback that is executed (notified) when the trackable object is detroyed. More...
void	notify_callbacks ()
	Execute and remove all previously installed callbacks. More...
trackable &	operator= (const trackable & src)
trackable &	operator= (trackable && src) noexcept
void	remove_destroy_notify_callback (notifiable *data) const
	Remove a callback previously installed with add_destroy_notify_callback(). More...

Additional Inherited Members
Public Types inherited from sigc::trackable_signal_with_accumulator< T_return, T_accumulator, T_arg... >
using	slot_type = slot< T_return(T_arg...)>
Public Types inherited from sigc::signal_base
using	size_type = std::size_t
Public Types inherited from sigc::trackable
using	func_destroy_notify = internal::func_destroy_notify
Public Types inherited from sigc::notifiable
using	func_destroy_notify = internal::func_destroy_notify
Protected Types inherited from sigc::signal_base
using	iterator_type = internal::signal_impl::iterator_type
Protected Member Functions inherited from sigc::signal_base
iterator_type	connect (const slot_base & slot_)
	Adds a slot at the end of the list of slots. More...
iterator_type	connect (slot_base && slot_)
	Adds a slot at the end of the list of slots. More...
iterator_type	connect_first (const slot_base & slot_)
	Adds a slot at the beginning of the list of slots. More...
iterator_type	connect_first (slot_base && slot_)
	Adds a slot at the beginning of the list of slots. More...
std::shared_ptr< internal::signal_impl >	impl () const
	Returns the signal_impl object encapsulating the list of slots. More...
iterator_type	insert (iterator_type i, const slot_base & slot_)
	Adds a slot at the given position into the list of slots. More...
iterator_type	insert (iterator_type i, slot_base && slot_)
	Adds a slot at the given position into the list of slots. More...
Protected Attributes inherited from sigc::signal_base
std::shared_ptr< internal::signal_impl >	impl_
	The signal_impl object encapsulating the slot list. More...

Detailed Description

template<typename T_return, typename... T_arg>
template <typename T_accumulator>
class sigc::trackable_signal< T_return(T_arg...)>::accumulated< T_accumulator >

Like sigc::trackable_signal but the additional template parameter T_accumulator defines the accumulator type that should be used.

An accumulator is a functor that uses a pair of special iterators to step through a list of slots and calculate a return value from the results of the slot invocations. The iterators' operator*() executes the slot. The return value is buffered, so that in an expression like

a = (*i) * (*i); 

the slot is executed only once.

Example 1:

This accumulator calculates the arithmetic mean value:

struct arithmetic_mean_accumulator
{
  template<typename T_iterator>
  double operator()(T_iterator first, T_iterator last) const
  {
    double value_ = 0;
    int n_ = 0;
    for (; first != last; ++first, ++n_)
      value_ += *first;
    return value_ / n_;
  }
};

Example 2:

This accumulator stops signal emission when a slot returns zero:

struct interruptable_accumulator
{
  template<typename T_iterator>
  bool operator()(T_iterator first, T_iterator last) const
  {
    for (; first != last; ++first, ++n_)
      if (!*first) return false;
    return true;
  }
};

Since libsigc++ 3.4:

Constructor & Destructor Documentation

accumulated() [1/2]

template <typename T_return , typename... T_arg>

template <typename T_accumulator >

sigc::trackable_signal< T_return(T_arg...)>::accumulated< T_accumulator >::accumulated ( )

default

accumulated() [2/2]

template <typename T_return , typename... T_arg>

template <typename T_accumulator >

sigc::trackable_signal< T_return(T_arg...)>::accumulated< T_accumulator >::accumulated ( const accumulated &  src )

inline