Question

this is my first question here.

Writing some code, i receive this error from g++: “Entity was not declared in this scope”, in this context:

#ifndef Psyco2D_GameManager_
#define Psyco2D_GameManager_

#include <vector>
#include "Entity.h"

namespace Psyco2D{
    class GameManager{J
    private:
        std::vector<Entity> entities;
    };
}

#endif

This is the content of Entity.h:

#ifndef Psyco2D_Entity_
#define Psyco2D_Entity_

#include <string>
#include "GameManager.h"
#include "EntityComponent.h"


namespace Psyco2D{

    class Entity{
        friend class GameManager;

    private:
        /* Identificatore */
        std::string _name;

        /* Components list */
        std::map<const std::string, EntityComponent*> components;

    protected:
        Entity(const std::string name);

    public:
        inline const std::string getName() const{
            return this->_name;
        }

        void addComponent(EntityComponent* component, const std::string name);

        EntityComponent* lookupComponent(const std::string name) const;

        void deleteComponent(const std::string name);

    };

}

#endif

If i use std::vector<class Entity> instead of std::vector<Entity> it works.

Why?

Thanks to all =)

Answer 1

Assuming the first snippet is part of GameManager.h you have a circular header dependency. I believe you can fix this by changing the GameManager.h include in Entity.h to class GameManager; instead.

Additionally as GMan noted, Entity is in a namespace and you need to qualify Entity with the namespace name.