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winrt::delegate struct template (C++/WinRT)

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A type that you can use to declare a custom delegate type for your own events. delegate supports any number of parameters, and they are not limited to Windows Runtime types.

The delegate type has no ABI (it has no interface for use across application binaries), so its use case is when you're both authoring and consuming an event within the same project. For more details of that scenario, see Parameterized delegates, simple signals, and callbacks within a project.

For more info about handling events, and code examples, see Handle events by using delegates in C++/WinRT.

Syntax

template <typename... T>
struct delegate : Windows::Foundation::IUnknown

Template parameters

typename... T A variadic template parameter pack containing the types of the parameters that the delegate is passed when it's called.

Requirements

Minimum supported SDK: Windows SDK version 10.0.17134.0 (Windows 10, version 1803)

Namespace: winrt

Header: %WindowsSdkDir%Include<WindowsTargetPlatformVersion>\cppwinrt\winrt\base.h (included by default)

Constructors

Constructor Description
delegate::delegate constructor Initializes a new instance of the delegate struct from the input data.

Member operators

Operator Description
delegate::operator() (function call operator) Invokes the delegate represented by the delegate object with the provided arguments.

delegate::delegate constructor

Initializes a new instance of the delegate struct from the input data.

Syntax

delegate(std::nullptr_t = nullptr) noexcept;

template <typename L>
delegate(L lHandler);

template <typename F>
delegate(F* fHandler);

template <typename O, typename M>
delegate(O* object, M method);

Template parameters

typename L A lambda function type.

typename F A free function type.

typename O An object type.

typename M A pointer-to-member-function type.

Parameters

lHandler A lambda function, which will handle the event.

fHandler A pointer-to-free-function, which will handle the event.

object A pointer to an object, one of whose member functions will handle the event.

method A pointer-to-member-function, which will handle the event.

delegate::operator() (function call operator)

Invokes the delegate represented by the delegate object with the provided arguments.

Syntax

void operator()(T const&... args) const

See also