CODEWITHSUNDEEP
asynchronousuwptaskc++-cx
Abi Ibrahiem
Abi Ibrahiem

Reputation: 3

create_task that calls ref class sealed constructor gives 'create_task': no matching overloaded function found

I have created to call the constructor of MyClass, My class is defined as ref class Myclass sealed and this function is defined as static under public

IAsyncOperation<MyClass^>^ MyNameSpace::MyClass::CreateAsync()
{
    return create_task(MyClass()).then([](MyClass^ objectx)
    {
        return ref new MyClass();
        //return std::make_shared<MyClass>();
    });
}

this is giving me bunch of errors like:

Error   C2672   'Concurrency::details::declval': no matching overloaded function found

Error   C2770   invalid explicit template argument(s) for '_Ty &&Concurrency::details::declval(void)'

Error   C2672   'Concurrency::details::_FilterValidTaskType': no matching overloaded function found

Error   C2672   'create_task': no matching overloaded function found

Upvotes: 0

Views: 161

Answers (1)

Peter Torr
Peter Torr

Reputation: 12019

Your constructor is not an asynchronous operation so can't be used as a parameter to create_task. If it takes a long time and you want to run the constructor as a task, use create_async instead.

create_async takes a function-like object (eg a lambda) and runs it as a task.

From your example above:

IAsyncOperation<MyClass^>^ MyNameSpace::MyClass::CreateAsync()
{
    return concurrency::create_async([]
    {
        return ref new MyClass();
    });
}

This will spin up a task to run the lambda (which constructs your class) and then wraps it in a WinRT IAsyncOperation<> that you can use. Since your constructor doesn't do anything, I'm not sure why you want it to be asynchronous though (unless you omitted a bunch of expensive calls).

Upvotes: 1

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