xtd::event< object_t, handler_t > Class Template Reference

Inheritance diagram for xtd::event< object_t, handler_t >:

Definition

template<typename object_t, typename handler_t>
class xtd::event< object_t, handler_t >

Represents an event.

Namespace

xtd

Library

xtd.core

Template Parameters

object_t	the owner object type of the event.
handler_t	Typically a xtd::event_handler or inherited type.

Remarks

Only an object of type object_t can be create and invoke event.

For more info about events see Events guide.

Examples

The following example cshow hot to use event.

#include <xtd/as>
#include <xtd/console>
#include <xtd/environment>
#include <xtd/event>
#include <xtd/event_handler>
#include <xtd/string>
 
class control : public xtd::object {
public:
  control() = default;
  
  const xtd::string& text() const {return text_;}
  void text(const xtd::string& text) {
    if (text_ != text) {
      text_ = text;
      on_text_changed(xtd::event_args::empty);
    }
  }
  
  xtd::event<control, xtd::event_handler> text_changed;
  
protected:
  void on_text_changed(const xtd::event_args& e) {text_changed(*this, e);}
  
private:
  xtd::string text_;
};
 
class button : public control {
public:
  button() = default;
  
  xtd::event<button, xtd::event_handler> click;
  
  void perform_click() {on_click(xtd::event_args::empty);}
  
protected:
  virtual void on_click(const xtd::event_args& e) {click(*this, e);}
};
 
auto main() -> int {
  auto button1 = button {};
  
  button1.text_changed += [](xtd::object & sender, const xtd::event_args & e)  {
    xtd::console::out << "text_changed [text=" << xtd::as<control>(sender).text() << "]" << xtd::environment::new_line;
  };
  
  button1.click += []  {
    xtd::console::out << "click on button1" << xtd::environment::new_line;
  };
  
  button1.text("button1");
  
  // click simulation
  button1.perform_click();
}
 
// This code produces the following output :
//
// text_changed [text=button1]
// click on button1

Examples

event.cpp, form_custom_event.cpp, graph_control.cpp, numeric_text_box.cpp, and send_message_to_form.cpp.

Public Methods
bool	is_empty () const noexcept
	Gets a value indicate if the event is empty.

Operators
handler_t &	operator+= (const handler_t &handler) noexcept
	Adds an handler to the event.
handler_t &	operator+= (const typename handler_t::function_t &function) noexcept
	Adds a function to the event.
template<typename fn_t >
handler_t &	operator+= (fn_t function) noexcept
	Adds a function to the event.
handler_t &	operator-= (const handler_t &handler) noexcept
	Removes an handler to the event.
handler_t &	operator-= (const typename handler_t::function_t &function) noexcept
	Removes a function to the event.
template<typename fn_t >
handler_t &	operator-= (fn_t function) noexcept
	Removes a function to the event.
void	clear () noexcept
	Clear event.

Member Function Documentation

is_empty()

template<typename object_t , typename handler_t >

bool xtd::event< object_t, handler_t >::is_empty ( ) const

inlinenoexcept

Gets a value indicate if the event is empty.

Returns

true if evcent does not contains functions; otherwise false.

operator+=() [1/3]

template<typename object_t , typename handler_t >

handler_t & xtd::event< object_t, handler_t >::operator+= ( const handler_t &  handler )

inlinenoexcept

Adds an handler to the event.

Parameters

handler

Handler to add.

Returns

The current event instance.

operator+=() [2/3]

template<typename object_t , typename handler_t >

handler_t & xtd::event< object_t, handler_t >::operator+= ( const typename handler_t::function_t &  function )

inlinenoexcept

Adds a function to the event.

Parameters

handler

Function to add.

Returns

The current event instance.

operator+=() [3/3]

template<typename object_t , typename handler_t >

template<typename fn_t >

handler_t & xtd::event< object_t, handler_t >::operator+= ( fn_t  function )

inlinenoexcept

Adds a function to the event.

Parameters

function

Function to add.

Returns

The current event instance.

operator-=() [1/3]

template<typename object_t , typename handler_t >

handler_t & xtd::event< object_t, handler_t >::operator-= ( const handler_t &  handler )

inlinenoexcept

Removes an handler to the event.

Parameters

handler

Handler to remove.

Returns

The current event instance.

operator-=() [2/3]

template<typename object_t , typename handler_t >

handler_t & xtd::event< object_t, handler_t >::operator-= ( const typename handler_t::function_t &  function )

inlinenoexcept

Removes a function to the event.

Parameters

function

Function to remove.

Returns

The current event instance.

operator-=() [3/3]

template<typename object_t , typename handler_t >

template<typename fn_t >

handler_t & xtd::event< object_t, handler_t >::operator-= ( fn_t  function )

inlinenoexcept

Removes a function to the event.

Parameters

function

Function to remove.

Returns

The current event instance.

clear()

template<typename object_t , typename handler_t >

void xtd::event< object_t, handler_t >::clear ( )

inlinenoexcept

Clear event.

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The documentation for this class was generated from the following file:

• xtd.core/include/xtd/event.h