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

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

Definition

template<class 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/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
	Represents function type.
using	function_collection
	Represents the function collection 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<class object1_t, class 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<class object1_t, class 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 function_collection &	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, const xtd::any_object &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 object &obj) const noexcept override
	Determines whether this instance and another specified delegateType object have the same value.
bool	equals (const delegate &other) const noexcept override
	Determines whether this instance and another specified delegateType object have the same value.

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 array< 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
	object ()=default
	Create a new instance of the ultimate base class object.
virtual xtd::size	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<class object_t>
xtd::unique_ptr_object< 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.
virtual bool	equals (const delegate< result_t() > &) const noexcept=0
	Indicates whether the current object is equal to another object of the same type.
template<class object_a_t, class 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<class object_a_t, class 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<class result_t>

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

Represents function type.

function_collection

template<class result_t>

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

Represents the function collection type.

Constructor & Destructor Documentation

delegate() [1/4]

template<class result_t>

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

default

Initializes an empty delegate.

delegate() [2/4]

template<class 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<class result_t>

template<class object1_t, class object2_t>

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

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<class result_t>

template<class object1_t, class 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<class result_t>

const function_collection & xtd::delegate< result_t()>::functions ( ) const

inline

Gets the delegates array.

Returns

The delegates array.

is_empty()

template<class 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<class 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<class result_t>

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

inline

Clear delegates array.

begin_invoke() [1/3]

template<class 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/xtd>
 
auto main() -> int {
  auto d1 = delegate<int(const string&)> {[](const 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<class 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/xtd>
 
auto main() -> int {
  auto d1 = delegate<int(const string&)> {[](const 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<class result_t>

async_result xtd::delegate< result_t()>::begin_invoke	(	xtd::async_callback	async_callback,
		const xtd::any_object &	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/xtd>
 
auto main() -> int {
  auto d1 = delegate<int(const string&)> {[](const 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<class 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/xtd>
 
auto main() -> int {
  auto d1 = delegate<int(const string&)> {[](const 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<class 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/xtd>
 
auto main() -> int {
  auto d1 = delegate<int(const string&)> {[](const 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() [1/2]

template<class result_t>

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

inlineoverridevirtualnoexcept

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

Parameters

obj	The delegateType to compare.

Returns

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

Reimplemented from xtd::object.

equals() [2/2]

template<class result_t>

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

inlineoverridenoexcept

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

Parameters

other

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<class result_t>

static delegate xtd::delegate< result_t()>::combine ( const array< 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<class 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<class 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<class 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<class 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.

---

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

• xtd.core/include/xtd/delegate.hpp