[solved] access data globally within application

[sachi]

I am developing qt application which users can log. what is the best way to keep user details access globally within a application. global variable or static variable or there is another better way?

[SGaist]

Hi,

It's not the role of static variables and global variables are rather frown upon. You should rather consider using a singleton for that kind of things

[sachi]

can you explain more about singleton and its implementation. may be tutorial about how to use singleton on qt?

[slesa]

The singleton is part of the software design patterns.

The implementation is easy: make the ctor private and implement one public static function which creates the instance:

class Foo {
    private:
      static Foo* _instance;
      Test();
    public:
     static Foo* getInstance() {
      if (_instance==NULL)
        _instance = new Foo();
      return _instance;
    }

cpp:

Foo::_instance = NULL;

And, please, put not all 'global variables' into one place, but consider the SOLID principles ;)