Call destructor and then constructor (resetting an object)

Question

I want to reset an object. Can I do it in the following way?

anObject->~AnObject();
anObject = new(anObject) AnObject();
// edit: this is not allowed: anO         


        

Answer 1

You cannot call the constructor in the manner indicated by you. Instead, you can do so using placement-new (like your code also indicates):

new (anObject) AnObject();

This code is guaranteed to be well-defined if the memory location is still available – as it should be in your case.

(I've deleted the part about whether this is debatable code or not – it's well-defined. Full stop.)

By the way, Brock is right: how the implementation of delete isn't fixed – it is not the same as calling the destructor, followed by free. Always pair calls of new and delete, never mix one with the other: that's undefined.