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1951. Virtual destructors are useful when you might potentially delete an instance of a derived class through a pointer to base class: class Base { // some virtual methods};class Derived : public Base{ ~Derived() { // Do some important cleanup }}; Here, you'll notice that I didn't declare Base's destructor to be virtual.
A base class object should have a virtual destructor, when it is necessary for the base class to do its own cleanup. This is to say, if you have allocated resources in the base class it is necessary for the base class to cleanup, by declaring its destructor virtual you guarantee that this cleanup will be done (assuming you wrote the cleanup ...
The recommendation is to insert: virtual ~criterion () {} Starting from C++11, you can use = default; instead of an empty body {}. This is to avoid problems with deleting from a base class' pointer. Otherwise you will leak memory as derived classes' destructors will not be called.
virtual ~A() = 0; }; inline A::~A() { } should suffice. If you derive anything from A and then try to delete or destroy it, A 's destructor will eventually be called. Since it is pure and doesn't have an implementation, undefined behavior will ensue. On one popular platform, that will invoke the purecall handler and crash.
78. Yes, you can definitely use = default for such destructors. Especially if you were just going to replace it with {}. I think the = default one is nicer, because it's more explicit, so it immediately catches the eye and leaves no room for doubt. However, here are a couple of notes to take into consideration when doing so.
Yes, a destructor in a derived class can be omitted if it has nothing to do. And it doesn't matter whether or not its virtual. I would omit it if possible. And I always use either the virtual keyword or override for virtual functions in derived classes for reasons of clarity.
No. Unlike other virtual methods, where you would explicitly call the Base method from the Derived to 'chain' the call, the compiler generates code to call the destructors in the reverse order in which their constructors were called. answered Mar 24, 2009 at 14:34. itsmatt.
1. A non-virtual destructor is perfectly fine as long as you you don't want to use it as a base pointer for derived classes when deleting the object. If you its derived classes in a polymorphic way, passing and storing it with a base pointer and then deleting it then the answer is no, use a virtual destructor.
When you need to destruct objects through a base class pointer. When you need to do this, you must define the destructor to be virtual within the base class. Otherwise, your derived destructors won't get called, independent of whether they are defined or not, and whether they are virtual or not. Here is an example:
1. Yes; you can, and should, make a destructor virtual, whenever you have a child class which may be destroyed using a reference to the base class. Static code analysis tools will even complain if you don't offer a virtual destructor. Consider the following example: A() { a = new int; } virtual ~A() { delete a; }