How to capture a class member's class member in lambda

Question

I try to capture a certain class member's class member from within a function of class for a lambda.

To clarify: ClassA has a class member of type ClassB, which has a member C (e.g. a pointer). ClassA has a function that attaches a lambda to some object O. The lambda needs to refer to C (at the moment of lambda attachment to object O).

The more specific code I am using is this. Where decide is another class function which takes an Answer object. i is my control variable of a for loop:

choices.back()->onClick([this, i] {decide(this->content->currentStep->answers[i]); });

The issue here is, that to my understanding, I capture this, which is a pointer, by value (which is fine). Once the lambda function body is executed though, to my understanding, it at that point in time dereferences content, currentStep and answers[]. So if the content pointer changes between setting and executing the lambda, the Answer object will be different from when I set the lambda.

What would the syntax look like for capturing the actual reference to answer itself instead of starting off from this->content->...?

Answer 1

The syntax would look like this.

choices.back()->onClick(
    [&answer=this->content->currentStep->answers[i]] {decide(answer);}
); // ^^^^^^ creating a named reference variable in the capture