Re: [Boost-users] [ASIO] destructor called multiple times in test code

From: Frank Birbacher (bloodymir.crap_at_[hidden])
Date: 2008-05-02 19:57:46

Hi!

Jose Martinez schrieb:
> I stumbled on the following behavior.  I created a class function object and overloaded the () operator and would call 
> 
>     t->async_wait(*this);

Function objects are passed by value. This call will copy your object. 
The other posts already pointed that out.

My recommendation is to follow common practise: make the operator() "const":

void operator () (/*...*/) const
{...}

That way you cannot modify members. The "state" of the functor must be 
stored outside of the functor object. This way the state doesn't get copied.

struct FunctorFoo
{
        FunctorFoo(int& counter)
        : counter(&counter)
        {}

        int* const counter;

        void operator() () const
        {
                ++*counter;
        }
};

(you could also use a "int& counter" member)

Frank