Andreas Huber wrote:
Hi John
John Maddock <john <at> johnmaddock.co.uk> writes:
# pragma warning( disable: 4511 ) // copy constructor could not be generated # pragma warning( disable: 4512 ) // assignment op could not be generated
IMO, these warnings are not very useful. Users will get heaps of them when they employ the library, so disabling them permanently is a good thing. I agree that they're useless, but I believe they'll still get suppressed for any instances of your templates that are instantiated if there is a matching #pragma warning(pop).
Correct. However, typical Statechart client code looks as follows:
#include <boost/statechart/simple_state.hpp>
struct MyMachine ....; struct MyState : sc::simple_state<MyState, MyMachine> { ... };
simple_state<> ultimately derives from noncopyable, which is why the warnings are generated in the first place. Popping at the end of the header would suppress the warnings for simple_state<> but would produce warnings for MyState. Since I believe that *all* users who care about warnings will disable these in their code anyway, I think the most user-friendly approach is to permanently disable them in the library header.
I'm not sure these warnings are caused by derivation from noncopyable. I tried to compile class A : private boost::noncopyable { }; in warning level 4 and got no warnings at all. I only get those 4511/4512 warnings when I write a class with a data member (not base class) that is not CopyConstrucible/Assignable. I solve these warnings either by suppressing them, or by declaring the copy-c'tor/assignment-op as private, and with no body (private declaration only).