How Ogre uses STL containers in an exported class without C4251 warning?

Question

OgrePrerequisites.h

#define _OgreExport __declspec( dllexport )

template <typename K, typename V, typename P = std::less<K>, typename A = STLAllocator<std::pair<const K, V>, GeneralAllocPolicy> > 
struct map 
{ 
   typedef typename std::map<K, V, P, A> type;
   typedef typename std::map<K, V, P, A>::iterator iterator;
   typedef typename std::map<K, V, P, A>::const_iterator const_iterator;
}

OgreLogManager.h

class _OgreExport LogManager
{
protected:
    typedef map<String, Log*>::type LogList;
    /// A list of all the logs the manager can access
    LogList mLogs;
};

The LogManager use std::map, but when I built the project, I didn't get any C4251 warning:

**class 'std::map<_Kty,_Ty>' needs to have dll-interface to be used by clients of class**

I want to know how Ogre eliminates the C4251 warning?

score 0 · Accepted Answer · answered Apr 28 '15 at 12:17

They explicitly disable certain warnings with #pragma warning. As mentioned on MSDN, the usual approach is to disable warnings locally with combination of

#pragma warning( push )
#pragma warning( disable : 4705 )
// Some code
#pragma warning( pop )

To restore original warning settings. They restore warning settings in OgreHeaderSuffix.h, so these warnings are disabled for library code only.

How Ogre uses STL containers in an exported class without C4251 warning?

1 Answers1