Insering javascript into html head from library

[eluser]nuwanda[/eluser]
If I want to make sure that some javascript is loaded every time a class is, what's the best way?

I've thought of providing a method that could be used like:

Code:

$this->someclass->inject_script();

Of course that would rely on the user making sure they used it correctly, which is no big deal but is there a way for my class to achieve the script injection without the use of the above method?

[eluser]CroNiX[/eluser]
Why reinvent the wheel?
http://ellislab.com/forums/viewthread/101236/ (I use this a lot)
http://ellislab.com/forums/viewthread/117966/

Im sure theres others of you search around for an asset manager.