Question

Boost has something like this:

void OnAccept( const boost::system::error_code & ec)
{
        if( ec )
        {
         ...
        }
}

error_code is a class. What operator to override to make a class object

Answer 1

You should use the safe bool idiom. This protects from most pitfalls that occur when you simply provide a conversion to bool.

To provide some context: If a type can be implicitly converted to bool through operator bool() const, a value of that type can be used in comparison expressions where this conversion doesn’t make any sense. The C++11 solution would be an explicit conversion operator.