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?