LinuxQuestions.org - Global access in C++

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Global access in C++

In my program I need to create a collection(which is a object) of objects when the program starts. I get all the data for the objects from a flat files I create when the program closes.

Now since my program will have a GUI, created with gtkmm, I need to be able to minipulate this collection. However, I don't have access to them from the widget functions.

How can I do this?

I don't follow. Why don't you have access to something from some functions? From where you have the access? (Sorry for being stupid, I really have no experience on gtk-libraries; only C++ and programming in general).

I think I know what you mean. This is accomplished by a pattern known as Singleton. With a singleton class you get a class that exists in exactly one instance and every component of your program can access that same object. Is this what you need? Then look at this:

The class declaration (.hh-file):

Code:

class MySingletonClass

{

public:



        // Singleton pattern

        static MySingletonClass *Instance();

        

        void AnyOtherMethod();



private:



        //Hide constructor and destructor from public

        MySingletonClass();

        ~MySingletonClass();



}; //class MySingletonClass

The class definition (.cc-file):

Code:

MySingletonClass *MySingletonClass::Instance()

{

        

        // Since the variable is static, this statement will only be

        // executed once, the first time execution reaches this point

        static MySingletonClass *sing = new MySingletonClass();



        return sing;

        

} //MySingletonClass *MySingletonClass::Instance()

Usage of the instance:

Code:

#include "MySingletonClass.hh"



// The Instance() method is static and can be accessed anywhere

// without any object reference.

MySingletonClass::Instance()->AnyOtherMethod();

Good luck with your project!
Martin

Ya I think the singleton pattern is exactly what I need. As soon as I read that word I remebered it from one of my OO clases from last year, I had completly forgot about it.

Currently I have it just setup as a global variable, which I know is bad. Once I get my program a little further I'll have to start using it with the singleton pattern.

I should really setup a little web site so that I can show you guys my progress. That way you can see where all you help is creating.