CODEWITHSUNDEEP
c++exceptionc++11constructor
Ralph Tandetzky
Ralph Tandetzky

Reputation: 23620

Is the destructor called when a delegating constructor throws?

It is well known that if a constructor throws, then all fully constructed sub-objects will be destroyed in reverse order including member data and all kinds of base classes. The destructor does not get called for non-delegating constructors though. For a delegating constructor the object has been constructed when the constructor body is entered, but construction continues somewhat. Therefore the question arises whether the destructor of the class is called, if the delegating constructor throws an exception from within its body? 

class X
{
public:
    X();
    X(int) : X() { throw std::exception(); } // is ~X() implicitely called?
    ~X();
};

Upvotes: 19

Views: 1705

Answers (2)

Stefano Falasca
Stefano Falasca

Reputation: 9097

The lifetime of an object begins when any constructor (i.e., in the case of delegation, the ultimate target constructor) is successfully completed. For the purposes of [C++03] §3.8, “the constructor call has completed” means any constructor call. This means that an exception thrown from the body of a delegating constructor will cause the destructor to be invoked automatically.

source.

And here is a nice article about delegating constructors, should anybody want to read it.

Upvotes: 7

James Kanze
James Kanze

Reputation: 153929

The rule is that the destructor is called for all fully constructed objects. The object is considered fully constructed once any constructor has finished, including the delegated constructor (even though the program continues in another constructor).

Upvotes: 16

Related Questions