task::task Constructor (C++ REST SDK)
Constructs a task object.
task();
template<
typename _Ty
>
__declspec(
noinline
) explicit task(_Ty _Param);
template<
typename _Ty
>
__declspec(
noinline
) explicit task(_Ty _Param, const task_options& _TaskOptions);
task(
const task& _Other
);
task(
task&& _Other
);
Parameters
_Ty
The type of the parameter from which the task is to be constructed._Param
The parameter from which the task is to be constructed. This could be a lambda, a function object, a task_completion_event<result_type> object, or a Windows::Foundation::IAsyncInfo if you are using tasks in your Windows Store app. The lambda or function object should be a type equivalent to std::function<X(void)>, where X can be a variable of type result_type, task<result_type>, or a Windows::Foundation::IAsyncInfo in Windows Store apps._TaskOptions
The task options include cancellation token, scheduler etc_Other
The source task object.
Remarks
The default constructor for a task is only present in order to allow tasks to be used within containers. A default constructed task cannot be used until you assign a valid task to it. Methods such as get, wait or then will throw an invalid_argument exception when called on a default constructed task.
A task that is created from a task_completion_event will complete (and have its continuations scheduled) when the task completion event is set.
The version of the constructor that takes a cancellation token creates a task that can be canceled using the cancellation_token_source the token was obtained from. Tasks created without a cancellation token are not cancelable.
Tasks created from a Windows::Foundation::IAsyncInfo interface or a lambda that returns an IAsyncInfo interface reach their terminal state when the enclosed Windows Runtime asynchronous operation or action completes. Similarly, tasks created from a lamda that returns a task<result_type> reach their terminal state when the inner task reaches its terminal state, and not when the lamda returns.
task behaves like a smart pointer and is safe to pass around by value. It can be accessed by multiple threads without the need for locks.
The constructor overloads that take a Windows::Foundation::IAsyncInfo interface or a lambda returning such an interface, are only available to Windows Store apps.
For more information, see Task Parallelism (Concurrency Runtime).
Requirements
Header: pplxtasks.h
Namespace: pplx