Global Object

[Phantom139]

I have completely forgot how to do this, or I'm thinking of another language.

How do I create in instance of an object that can be used throughout all of my .cpp files.

The class is defined in a header file so I'm just wondering if it is done through there.

IE: I have methods that use a class instance, and then in another file, more methods that use the same instance, only problem is, I cannot interface these two instances because it's two unique declarations of the same object, so pretty much, how do I have just one instance of the object that is used by all the functions, thus allowing me to interface between them.

[Bazzy]

Declare the object as extern
And instanciate it on one source file

[Phantom139]

Thanks for your help, I knew it was something like that, apparently it was.

[R0mai]

This is called singleton pattern.
This is an example how it could be implemented:

class singleton {
public:
    static singleton& getinstance() {
        static singleton instance;
        return instance;
    }
private:
    //Don't allow copying or constructing
    singleton() {}
    singleton(const singleton&) {}
    singleton& operator=(const singleton&) {}
};

//...
singleton& s = singleton::getinstance();

EDIT: you can use extern as well. I personally prefer singleton.

[sohguanh]

In Java we need to put in a synchronized keyword in case the getinstance() method is called by multiple threads at the same time. So how does C++ solve this problem ?

[R0mai]

In Java we need to put in a synchronized keyword in case the getinstance() method is called by multiple threads at the same time. So how does C++ solve this problem ?

http://lmgtfy.com/?q=java+synchronized+in+c%2B%2B