Deleting a reference

Question

Is this valid? An acceptable practice?

typedef vector intArray;

intArray& createArray()
{
    intArray *arr = new intArray(10000, 0);

    r         


        

Answer 1

Is this valid?

Yes.

An acceptable practice?

No.

This code has several problems:

• The guideline of designing for least surprising behavior is broken: you return something that "looks like" an object but must be deleted by the client code (that should mean a pointer - a reference should be something that always points to a valid object).

• your allocation can fail. Even if you check the result in the allocating function, what will you return? An invalid reference? Do you rely on the allocation throwing an exception for such a case?

As a design principle, consider either creating a RAII object that is responsible for managing the lifetime of your object (in this case a smart pointer) or deleting the pointer at the same abstraction level that you created it:

typedef vector intArray;

intArray& createArray()
{
    intArray *arr = new intArray(10000, 0);

    return(*arr);
}

void deleteArray(intArray& object)
{
    delete &object;
}

int main(int argc, char *argv[])
{
    intArray& array = createArray();
    //..........
    deleteArray(array);
    return 0;
}

This design improves coding style consistency (allocation and deallocation are hidden and implemented at the same abstraction level) but it would still make more sense to work through a pointer than a reference (unless the fact that your object is dynamically allocated must remain an implementation detail for some design reason).