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

It is far better just to add something like a Reset() method to your object rather than play with placement new's.

You are exploiting the placement new feature which is intended to allow you to control where an object is allocated. This is typically only an issue if your hardware has "special" memory like a flash chip. IF you want to put some objects in the flash chip, you can use this technique. The reason that it allows you to explicitly call the destructor is that YOU are now in control of the memory, so the C++ compiler doesn't know how to do the deallocation part of the delete.

It is not saving you much code either, with a reset method, you will have to set the members to their starting values. malloc() doesn't do that so you are going to have to write that code in the constructor anyway. Just make a function that sets your members to the starting values, call it Reset() call it from the constructor and also from anywhere else you need.