C++ Compiler or Linker optimization

Question

I'm trying to create an autoload class system using class mapping as specified in best answere of this post:

Is there a way to instantiate objects from a string holding their class name?

so i've created this code based on my needs:

// ScriptLoader.h
template<class TScript> void createScript() { 
    new TScript; 
}

struct ScriptFactory {
public:
    typedef void(*ScriptCreatorFunc)();
    typedef std::map<std::string,ScriptCreatorFunc> ScriptCreatorStorage;

    static ScriptCreatorStorage ScriptCreators;

    static bool RegisterCreator(std::string const& s,ScriptCreatorFunc creator)
    {
        ASSERT(ScriptCreators.find(s) == ScriptCreators.end());   // prevent registering the same script twice
        ScriptCreators.insert(std::make_pair(s,creator));
        return true;
    }
};

template<class TScript>
struct ScriptReg : ScriptFactory { 
    ScriptReg(std::string const& s) { 
        ScriptFactory::RegisterCreator(s,&createScript<TScript>);
    }
};

class ScriptLoader {
public:
    static void AddScripts()
    {
        for (ScriptFactory::ScriptCreatorStorage::iterator itr = ScriptFactory::ScriptCreators.begin(); itr != ScriptFactory::ScriptCreators.end(); ++itr)
            itr->second();
    }    
};

#define REGISTER_DEC_TYPE(NAME) \
    static ScriptReg<NAME> reg

#define REGISTER_DEF_TYPE(NAME) \
    ScriptReg<NAME> NAME::reg(#NAME)


// ScriptLoader.cpp
ScriptFactory::ScriptCreatorStorage ScriptFactory::ScriptCreators;

// foo.cpp
class foo:
{
    public:

        foo()
        {
                /* code */
        }

    private:
        REGISTER_DEC_TYPE(foo);
};

REGISTER_DEF_TYPE(foo);

and of course i've defined REGISTER_DEC_TYPE in a foo class and at bottom of foo.cpp file i've put: REGISTER_DEF_TYPE(foo) ... ( AddScripts function instead is called by main program so it's normally linked in binaries )

it compiles well but when i try to debug , i cannot set breakpoints in visual studio that shows this tip: "No executable code is associated with this line. Possible causes include: preprocessor directive or compiler/linker optimization"

and in foo.cpp it shows: "any symbol has been loaded for this document"

so i guess the compiler don't find any "normal" call to these functions/classes removing them from the binary code.

Is there any way to avoid this kind of optimization? i'm finding a crossplatform solution to this problem.

thanks in advance

Answer 1

Deadstripping is a common problem with factory code. What you usually have to do is have a function somewhere that uses all of your types. It's ugly but unfortunately there are no particularly elegant portable solutions.