Question

I am attempting to create a simple base class and another class that inherits from it. I am getting the following error.

guard_room.h:17:1: error: expected class-name before ‘{’ token

I have looked at other posts and it seems like I have a circular dependency somewhere but I have done everything I have read to resolve it. Here are my classes

Base class room.h:

#ifndef _room
#define _room

template <typename U, typename T>
class room
{
    public:

        //default constructor
        room();

        //overloaded constructor
        room(U, T);


        //getters/setters
        void set_treasure(T);
        void set_name(U);
        T get_treasure() const;
        U get_name() const;

    private:

        U name;

        //room monster
        //monster room_monster

        T treasure;

};

#include "room.tem"

#endif

Inherited class guard_room.h:

#ifndef _guard_room
#define _guard_room

template <typename U, typename T> class room;

template <typename U, typename T>
class guard_room : public room
{
    public:

        //default constructor
        guard_room();

        //overloaded constructor
        guard_room(U, T, T) : room(U, T);

        //battle function?
        void battle();

    private:
        T dummy;

};

#include "guard_room.tem"
#endif

I am also thoroughly confused in where I need to put the includes for the base room class in my inherited class. Thanks for your help with this.

Answer 1

Firstly, your derived class needs to be able to see the entire definition of your base class – you’ll need to include the header at the top of the derived class’ file. (a base class extends a derived class, so the base class is very much a part of the derived class)

Also, room is a template and not a class – you can only inherit from a concrete class, so you need to specify the template parameters. i.e.

#include "room.h"

template <typename U, typename T>
class guard_room : public room<U, T>

Lastly – do your .tem files also contain header guards? (If not, you’ll need those in there too to avoid other compiler errors)

---

Also, be aware that an initialiser list is part of a constructor’s definition, so the following is invalid

    guard_room(U, T, T) : room(U, T);

If your constructor definition is elsewhere, then all you want here is

    guard_room(U, T, T);

otherwise, it might just be enough to write

    guard_room(U u, T t1, T t2) : room(u, t1) {}