xtd::delegate< result_t()> Class Template Reference

Inheritance diagram for xtd::delegate< result_t()>:

Definition

template<typename result_t>
class xtd::delegate< result_t()>

Represents a delegate, which is a data structure that refers to a static method or to a class instance && an instance method of that class.

Header

#include <xtd/delegate>

Namespace

xtd

Library

xtd.core

Remarks

For more info about delegates see Delegates guide.

Examples

The following example shows how to define a delegate named my Method delegate. Instances of this delegate are created for an instance method && a static method of the nested mySampleClass class. The delegate for the instance method requires an instance of mySampleClass. The mySampleClass instance is saved in a variable named mySC.

#include <xtd/console>
#include <xtd/delegate>
 
using namespace xtd;
 
void goodbye(const string& s) {
  console::write_line("Goodbye {}", s);
}
 
class object {
public:
  void hello(const string& s) {
    console::write_line("Hello {}", s);
  }
};
 
auto main() -> int {
  using example_function = delegate<void(const string&)>;
  auto instance = ::object {};
  auto str = string {"World"};
  
  //equivanet to : example_function f = {std::bind(&::object::hello, &instance, std::placeholders::_1)};
  auto f = example_function {instance, &::object::hello};
  
  // equivalent to : instance.hello(str)
  f(str);
  f = goodbye;
  
  // equivalent to : goodbye(str)
  f(str);
  return 0;
}
 
// This code produces the following output :
//
// Hello, World
// Goodbye, World

Public Aliases
using	function_t = std::function< result_t()>
	function_t pointer type

Public Constructors
	delegate ()=default
	Initializes an empty delegate.
	delegate (const function_t &function) noexcept
	Initializes a delegate that invokes the specified instance method.
template<typename object1_t , typename object2_t >
	delegate (const object1_t &object, result_t(object2_t::*method)() const) noexcept
	Initializes a delegate that invokes the specified instance method on the specified class instance.
template<typename object1_t , typename object2_t >
	delegate (const object1_t &object, result_t(object2_t::*method)()) noexcept
	Initializes a delegate that invokes the specified instance method on the specified class instance.

Public Properties
const std::vector< function_t > &	functions () const
	Gets the delegates array.
bool	is_empty () const noexcept
	Return if the delegate is empty.
size_t	size () const noexcept
	Return the size of invocation list.

Public Methods
void	clear ()
	Clear delegates array.
async_result	begin_invoke ()
	Executes the method represented by the current delegate asynchronously on the thread that the control's underlying handle was created on.
async_result	begin_invoke (xtd::async_callback async_callback)
	Executes the method represented by the current delegate asynchronously on the thread that the control's underlying handle was created on.
async_result	begin_invoke (xtd::async_callback async_callback, std::any async_state)
	Executes the method represented by the current delegate asynchronously on the thread that the control's underlying handle was created on.
result_t	end_invoke (async_result async)
	Retrieves the return value of the asynchronous operation represented by the async_result_invoke passed.
result_t	invoke () const
	invokes the method represented by the current delegate.
bool	equals (const delegate &delegate) const noexcept override
	Determines whether this instance and another specified delegateType object have the same value.
virtual bool	equals (const object &obj) const noexcept
	Determines whether the specified object is equal to the current object.
template<typename object_a_t , typename object_b_t >
static bool	equals (const object_a_t &object_a, const object_b_t &object_b) noexcept
	Determines whether the specified object instances are considered equal.

Operators
result_t	operator() () const
	invokes the method represented by the current delegate.
delegate &	operator= (const function_t &function) noexcept

Public Static Methods
static delegate	combine (const std::vector< delegate > &delegates) noexcept
	Concatenates the invocation lists of an array of delegates.
static delegate	combine (const delegate &a, const delegate &b) noexcept
	Concatenates the invocation lists of two delegates.
static delegate	remove (const delegate &source, const delegate &value) noexcept
	removes the last occurrence of the invocation list of a delegate from the invocation list of another delegate.
static delegate	remove_all (const delegate &source, const delegate &value) noexcept
	removes all occurrences of the invocation list of a delegate from the invocation list of another delegate.

Additional Inherited Members
Public Member Functions inherited from xtd::object
	object ()=default
	Create a new instance of the ultimate base class object.
virtual size_t	get_hash_code () const noexcept
	Serves as a hash function for a particular type.
virtual type_object	get_type () const noexcept
	Gets the type of the current instance.
template<typename object_t >
xtd::uptr< object_t >	memberwise_clone () const
	Creates a shallow copy of the current object.
virtual xtd::string	to_string () const noexcept
	Returns a xtd::string that represents the current object.
Public Member Functions inherited from xtd::iequatable< delegate< result_t()> >
virtual bool	equals (const delegate< result_t()> &) const noexcept=0
	Indicates whether the current object is equal to another object of the same type.
Static Public Member Functions inherited from xtd::object
template<typename object_a_t , typename object_b_t >
static bool	equals (const object_a_t &object_a, const object_b_t &object_b) noexcept
	Determines whether the specified object instances are considered equal.
template<typename object_a_t , typename object_b_t >
static bool	reference_equals (const object_a_t &object_a, const object_b_t &object_b) noexcept
	Determines whether the specified object instances are the same instance.

Member Typedef Documentation

function_t

template<typename result_t >

using xtd::delegate< result_t()>::function_t = std::function <result_t()>

function_t pointer type

Constructor & Destructor Documentation

delegate() [1/4]

template<typename result_t >

xtd::delegate< result_t()>::delegate ( )

default

Initializes an empty delegate.

delegate() [2/4]

template<typename result_t >

xtd::delegate< result_t()>::delegate ( const function_t &  function )

inlinenoexcept

Initializes a delegate that invokes the specified instance method.

Parameters

function

the method instance.

delegate() [3/4]

template<typename result_t >

template<typename object1_t , typename object2_t >

xtd::delegate< result_t()>::delegate ( const object1_t &  object, result_t(object2_t::*)() const  method  )

inlinenoexcept

Initializes a delegate that invokes the specified instance method on the specified class instance.

Parameters

object	the class instance.
function	the method instance.

delegate() [4/4]

template<typename result_t >

template<typename object1_t , typename object2_t >

xtd::delegate< result_t()>::delegate ( const object1_t &  object, result_t(object2_t::*)()  method  )

inlinenoexcept

Initializes a delegate that invokes the specified instance method on the specified class instance.

Parameters

object	the class instance.
function	the method instance.

Member Function Documentation

functions()

template<typename result_t >

const std::vector< function_t > & xtd::delegate< result_t()>::functions ( ) const

inline

Gets the delegates array.

Returns

The delegates array.

is_empty()

template<typename result_t >

bool xtd::delegate< result_t()>::is_empty ( ) const

inlinenoexcept

Return if the delegate is empty.

Returns

bool Return true if delegate is empty; otherwise false.

size()

template<typename result_t >

size_t xtd::delegate< result_t()>::size ( ) const

inlinenoexcept

Return the size of invocation list.

Returns

Return the size of invocation list.

clear()

template<typename result_t >

void xtd::delegate< result_t()>::clear ( )

inline

Clear delegates array.

begin_invoke() [1/3]

template<typename result_t >

async_result xtd::delegate< result_t()>::begin_invoke

(

)

Executes the method represented by the current delegate asynchronously on the thread that the control's underlying handle was created on.

Returns

An async_result_invoke that represents the result of the begin_invoke operation.

Examples

The following examples shows hot tu use xtd::delegate::begin_invoke, xtd::delegate::end_invoke, xtd::delegate::invoke methods.

#include <xtd/threading/thread>
#include <xtd/console>
#include <xtd/delegate>
 
using namespace xtd;
using namespace xtd::threading;
 
auto main() -> int {
  auto d1 = delegate<int(string)> {[](string name) -> int {
    console::write_line("(Thread {}) Hello {}!", thread::current_thread().managed_thread_id(), name);
    return name == "xtd" ? 42 : 24;
  }};
  
  auto result = d1.begin_invoke("Gammasoft");
  console::write_line("return = {}", d1.invoke("xtd"));
  console::write_line("return = {}", d1.end_invoke(result));
}
 
// This code produces the following output :
//
// (Thread 1) Hello xtd!
// return = 42
// (Thread 4) Hello Gammasoft!
// return = 24

begin_invoke() [2/3]

template<typename result_t >

async_result xtd::delegate< result_t()>::begin_invoke

(

xtd::async_callback

async_callback

)

Executes the method represented by the current delegate asynchronously on the thread that the control's underlying handle was created on.

Parameters

async_callback

The asynchronous callback that will be called at the end of the invocation.

Returns

An async_result_invoke that represents the result of the begin_invoke operation.

Examples

The following examples shows hot tu use xtd::delegate::begin_invoke, xtd::delegate::end_invoke, xtd::delegate::invoke methods.

#include <xtd/threading/thread>
#include <xtd/console>
#include <xtd/delegate>
 
using namespace xtd;
using namespace xtd::threading;
 
auto main() -> int {
  auto d1 = delegate<int(string)> {[](string name) -> int {
    console::write_line("(Thread {}) Hello {}!", thread::current_thread().managed_thread_id(), name);
    return name == "xtd" ? 42 : 24;
  }};
  
  auto result = d1.begin_invoke("Gammasoft");
  console::write_line("return = {}", d1.invoke("xtd"));
  console::write_line("return = {}", d1.end_invoke(result));
}
 
// This code produces the following output :
//
// (Thread 1) Hello xtd!
// return = 42
// (Thread 4) Hello Gammasoft!
// return = 24

begin_invoke() [3/3]

template<typename result_t >

async_result xtd::delegate< result_t()>::begin_invoke	(	xtd::async_callback	async_callback,
		std::any	async_state
	)

Executes the method represented by the current delegate asynchronously on the thread that the control's underlying handle was created on.

Parameters

async_callback	The asynchronous callback that will be called at the end of the invocation.
async_state	The asynchronous state associated with the invocation.

Returns

An async_result_invoke that represents the result of the begin_invoke operation.

Examples

The following examples shows hot tu use xtd::delegate::begin_invoke, xtd::delegate::end_invoke, xtd::delegate::invoke methods.

#include <xtd/threading/thread>
#include <xtd/console>
#include <xtd/delegate>
 
using namespace xtd;
using namespace xtd::threading;
 
auto main() -> int {
  auto d1 = delegate<int(string)> {[](string name) -> int {
    console::write_line("(Thread {}) Hello {}!", thread::current_thread().managed_thread_id(), name);
    return name == "xtd" ? 42 : 24;
  }};
  
  auto result = d1.begin_invoke("Gammasoft");
  console::write_line("return = {}", d1.invoke("xtd"));
  console::write_line("return = {}", d1.end_invoke(result));
}
 
// This code produces the following output :
//
// (Thread 1) Hello xtd!
// return = 42
// (Thread 4) Hello Gammasoft!
// return = 24

end_invoke()

template<typename result_t >

result_t xtd::delegate< result_t()>::end_invoke

(

async_result

async

)

Retrieves the return value of the asynchronous operation represented by the async_result_invoke passed.

Parameters

async

The async_result_invoke that represents a specific invoke asynchronous operation, returned when calling begin_invoke.

Examples

The following examples shows hot tu use xtd::delegate::begin_invoke, xtd::delegate::end_invoke, xtd::delegate::invoke methods.

#include <xtd/threading/thread>
#include <xtd/console>
#include <xtd/delegate>
 
using namespace xtd;
using namespace xtd::threading;
 
auto main() -> int {
  auto d1 = delegate<int(string)> {[](string name) -> int {
    console::write_line("(Thread {}) Hello {}!", thread::current_thread().managed_thread_id(), name);
    return name == "xtd" ? 42 : 24;
  }};
  
  auto result = d1.begin_invoke("Gammasoft");
  console::write_line("return = {}", d1.invoke("xtd"));
  console::write_line("return = {}", d1.end_invoke(result));
}
 
// This code produces the following output :
//
// (Thread 1) Hello xtd!
// return = 42
// (Thread 4) Hello Gammasoft!
// return = 24

invoke()

template<typename result_t >

result_t xtd::delegate< result_t()>::invoke ( ) const

inline

invokes the method represented by the current delegate.

Parameters

arguments

The parameter list.

Returns

result_t The return value.

Examples

The following examples shows hot tu use xtd::delegate::begin_invoke, xtd::delegate::end_invoke, xtd::delegate::invoke methods.

#include <xtd/threading/thread>
#include <xtd/console>
#include <xtd/delegate>
 
using namespace xtd;
using namespace xtd::threading;
 
auto main() -> int {
  auto d1 = delegate<int(string)> {[](string name) -> int {
    console::write_line("(Thread {}) Hello {}!", thread::current_thread().managed_thread_id(), name);
    return name == "xtd" ? 42 : 24;
  }};
  
  auto result = d1.begin_invoke("Gammasoft");
  console::write_line("return = {}", d1.invoke("xtd"));
  console::write_line("return = {}", d1.end_invoke(result));
}
 
// This code produces the following output :
//
// (Thread 1) Hello xtd!
// return = 42
// (Thread 4) Hello Gammasoft!
// return = 24

equals() [1/3]

template<typename result_t >

bool xtd::delegate< result_t()>::equals ( const delegate< result_t()> &  delegate ) const

inlineoverridenoexcept

Determines whether this instance and another specified delegateType object have the same value.

Parameters

value

The delegateType to compare.

Returns

bool true if the value of this instance is the same as the value of value; otherwise, false.

combine() [1/2]

template<typename result_t >

static delegate xtd::delegate< result_t()>::combine ( const std::vector< delegate< result_t()> > &  delegates )

inlinestaticnoexcept

Concatenates the invocation lists of an array of delegates.

Parameters

delegates

The array of delegates to combine.

Returns

Delegate A new delegate with an invocation list that concatenates the invocation lists of the delegates in the delegates array. Returns null if delegates is null, if delegates contains zero elements, || if every entry in delegates is null.

Remarks

If the delegates array contains entries that are null, those entries are ignored.

The invocation list can contain duplicate entries; that is, entries that refer to the same method on the same object.

combine() [2/2]

template<typename result_t >

static delegate xtd::delegate< result_t()>::combine ( const delegate< result_t()> &  a, const delegate< result_t()> &  b  )

inlinestaticnoexcept

Concatenates the invocation lists of two delegates.

Parameters

a	The delegate whose invocation list comes first.
b	The delegate whose invocation list comes second.

Returns

delegateType A new delegate with an invocation list that concatenates the invocation lists of a and b in that order. Returns a if b is null, returns b if a is a null reference, and returns a null reference if both a and b are null references.

Remarks

The invocation list can contain duplicate entries; that is, entries that refer to the same method on the same object.

remove()

template<typename result_t >

static delegate xtd::delegate< result_t()>::remove ( const delegate< result_t()> &  source, const delegate< result_t()> &  value  )

inlinestaticnoexcept

removes the last occurrence of the invocation list of a delegate from the invocation list of another delegate.

Parameters

source	The delegate from which to remove the invocation list of value.
value	The delegate that supplies the invocation list to remove from the invocation list of source.

Returns

delegate A new delegate with an invocation list formed by taking the invocation list of source and removing the last occurrence of the invocation list of value, if the invocation list of value is found within the invocation list of source. Returns source if value is null || if the invocation list of value is ! found within the invocation list of source. Returns a null reference if the invocation list of value is equal to the invocation list of source || if source is a null reference.

Remarks

If the invocation list of value matches a contiguous set of elements in the invocation list of source, then the invocation list of value is said to occur within the invocation list of source. If the invocation list of value occurs more than once in the invocation list of source, the last occurrence is removed.

remove_all()

template<typename result_t >

static delegate xtd::delegate< result_t()>::remove_all ( const delegate< result_t()> &  source, const delegate< result_t()> &  value  )

inlinestaticnoexcept

removes all occurrences of the invocation list of a delegate from the invocation list of another delegate.

Parameters

source	The delegate from which to remove the invocation list of value.
value	The delegate that supplies the invocation list to remove from the invocation list of source.

Returns

delegate A new delegate with an invocation list formed by taking the invocation list of source && removing all occurrences of the invocation list of value, if the invocation list of value is found within the invocation list of source. Returns source if value is null || if the invocation list of value is ! found within the invocation list of source. Returns a null reference if the invocation list of value is equal to the invocation list of source, if source contains only a series of invocation lists that are equal to the invocation list of value, || if source is a null reference.

Remarks

If the invocation list of value matches a contiguous set of elements in the invocation list of source, then the invocation list of value is said to occur within the invocation list of source. If the invocation list of value occurs more than once in the invocation list of source, all occurrences are removed.

operator()()

template<typename result_t >

result_t xtd::delegate< result_t()>::operator() ( ) const

inline

invokes the method represented by the current delegate.

Parameters

arguments

The parameter list.

Returns

result_t The return value.

equals() [2/3]

template<typename result_t >

virtual bool xtd::object::equals ( const object &  obj ) const

virtualnoexcept

Determines whether the specified object is equal to the current object.

Parameters

obj	The object to compare with the current object.

Returns

true if the specified object is equal to the current object. otherwise, false.

Examples

The following code example compares the current instance with another object.

#include <xtd/console>
 
using namespace xtd;
 
auto main() -> int {
  auto object1 = new_ptr<object>();
  auto object2 = new_ptr<object>();
  
  auto object3 = object2;
  console::write_line(object1->equals(*object3));
  console::write_line(*object1 == *object3);
  object3 = object1;
  console::write_line(object1->equals(*object3));
  console::write_line(*object1 == *object3);
}
 
// This code produces the following output :
//
// false
// false
// true
// true

Reimplemented from xtd::object.

equals() [3/3]

template<typename result_t >

template<typename object_a_t , typename object_b_t >

static bool xtd::object::equals ( const object_a_t &  object_a, const object_b_t &  object_b  )

inlinestaticnoexcept

Determines whether the specified object instances are considered equal.

Parameters

object_a	The first object to compare.
object_b	The second object to compare.

Returns

true if object_a is the same instance as object_b or if both are null references or if object_a(object_b) returns true. otherwise, false.

Examples

The following code example compares different objects.

#include <xtd/console>
 
using namespace xtd;
 
auto main() -> int {
  string s1 = "Tom";
  string s2 = "Carol";
  console::write_line("object::equals(\"{0}\", \"{1}\") => {2}", s1, s2, object::equals(s1, s2));
  
  s1 = "Tom";
  s2 = "Tom";
  console::write_line("object::equals(\"{0}\", \"{1}\") => {2}", s1, s2, object::equals(s1, s2));
  
  s1 = "";
  s2 = "Tom";
  console::write_line("object::equals(\"{0}\", \"{1}\") => {2}", s1, s2, object::equals(s1, s2));
  
  s1 = "Carol";
  s2 = "";
  console::write_line("object::equals(\"{0}\", \"{1}\") => {2}", s1, s2, object::equals(s1, s2));
  
  s1 = "";
  s2 = "";
  console::write_line("object::equals(\"{0}\", \"{1}\") => {2}", s1, s2, object::equals(s1, s2));
}
 
// This code produces the following output :
//
// object::equals("Tom", "Carol") => false
// object::equals("Tom", "Tom") => true
// object::equals("", "Tom") => false
// object::equals("Carol", "") => false
// object::equals("", "") => true

---

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

• xtd.core/include/xtd/delegate.hpp