CODEWITHSUNDEEP
c++lambdacallback
Tono Nam
Tono Nam

Reputation: 36048

Using lambdas in local scope in c++

Is it OK to declare lambdas in local scope like this:

// reference to method is just a call back function. 
void(*referenceToSomeMethod)();

// store call back function
void foo(void(*pointerToMethod)())
{
    referenceToSomeMethod = pointerToMethod; // save reference to method    
}

int main()
{

    referenceToSomeMethod = nullptr;

    if (1 == 1)
    {
        // use of lambda on local scope
        foo([]() {
            printf("Executing callback function\n");
        });


    } // leaving scope lambda may not longer be valid?

    // simulate some work
    Sleep(10000);

    if (referenceToSomeMethod != nullptr)
        referenceToSomeMethod(); // execute lambda
}

In real life I wait until an event occurs to fire the callback method. Can I run the risk of the callback pointer pointing to a function that no longer exists?

I know this works in c# and other languages that have a garbage collector. But will this work on c++?

Upvotes: 1

Views: 331

Answers (1)

user2039981
user2039981

Reputation:

Lambdas with empty brackets are equivalent with function pointers and will be copied by value in the same way. Answer yes.

Upvotes: 2

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