Compile issue in g++, works fine in VS

Hi
The g++ compiler generates the following error output for the code below. This code compiles fine in Visual Studio. Any ideas as to why this code fails in g++?


factory.h: In member function ‘bool Factory<Base>::Register(ObjectType, CreatorBase<Base>*)’:
factory.h:45: error: expected `;' before ‘it’
factory.h:47: error: ‘it’ was not declared in this scope

Thanks
Ken

factory.h

Code:

 #ifndef FACTORY_
#define FACTORY_

#include <map>
#include <string>


typedef std::string ObjectType;


template<class Base>
class CreatorBase
{
public:
    virtual ~CreatorBase() {}
    virtual Base * Create() const = 0;
};



template<class Product, class Base>
class Creator : public CreatorBase<Base>
{
public:
    virtual Base * Create() const {return new Product;}
};



template<class Base>
class Factory
{
public:
    Base * Create(ObjectType type);
    bool Register(ObjectType type, CreatorBase<Base> * pCreator) ;
private:
	typedef std::map<ObjectType, CreatorBase<Base> *> CreatorMap;
    CreatorMap m_creatorMap;
};


template<class Base>
bool Factory<Base>::Register(ObjectType type, CreatorBase<Base> * pCreator)
{
    CreatorMap::iterator  it = m_creatorMap.find(type);
    
    if (it != m_creatorMap.end()) {
        delete pCreator;
        return false;
    }
    m_creatorMap[type] = pCreator;
    return true;
}

template<class Base>
Base * Factory<Base>::Create(ObjectType type)
{
    CreatorMap::iterator it = m_creatorMap.find(type);
    if (it == m_creatorMap.end()) 
        return NULL;

    CreatorBase<Base> * pCreator = (*it).second;
    return pCreator->Create();
}



#endif /*FACTORY_*/

entity.h

Code:

#ifndef ENTITY_H_
#define ENTITY_H_

class GameEntity
{
public:
    virtual ~GameEntity() {}
    virtual const char * GetClassName() { return "GameEntity"; }

};


class GameCamera : public GameEntity
{
public:
    virtual const char * GetClassName() { return "GameCamera"; }

};

#endif /*ENTITY_H_*/

main.c++

Code:

#include <iostream>

#include "factory.h"
#include "entity.h"

int 
main() {


std::cout << "Hello World" << std::endl;

Factory<GameEntity> factory;

factory.Register(GameCamera, new Creator<GameCameram,GameEntity>);

}

That should be a rather standard issue. What CreatorMap::iterator is depends on the template type arguments, and in such cases in standard C++ it is required to disambiguate whether it is or is not a typename by using the typename keyword:

Code:

    typename CreatorMap::iterator  it = m_creatorMap.find(type);

Without the typename keyword, according to C++ standard, iterator should be interpreted as a static member of CreatorMap or something like that.

MSVC doesn't require that (as an extension?).

Originally Posted by anon

MSVC doesn't require that (as an extension?).

Due toe the way it parses the code more likely, I would say.
But yes, VC++ is known not to be the best strict compiler when it comes to adhering to the standard.

It depends on which version of VC++ you use. Older versions required you to do it the wrong way (without the typename). Newer versions fixed that, although I'm not sure whether they also allow the old way for backwards compatibility.

Thanks Anon! That was the problem exactly.

For others: this was done using MSVS 2008...