[cairo] cairo_set_user_data () and other "set_user_data" functions

[Daniel Goldman]

> 

> > When might I want to  use cairo_set_user_data () and the other 
>"set_user_data" 
>
> > functions? I  understand what cairo_set_user_data () does.
> 
> Whenever you wish to attach  some non-cairo data to a cairo object.  
> Typically, you'd attach a  resource whose lifetime is dependent on the 
> lifetime of the cairo object,  thereby passing ownership of the 
> resource to the cairo object.
> 
> >  But I looked through 
> > the docs and archive and couldn't see any examples  or guidance related to 
> > real-world use.
> 
> Koders.com or google code search are a great tools  for finding 
> real-world uses of APIs.  For  instance
> 
> http://www.koders.com/default.aspx?s="cairo_surface_set_user_data"
> 
> Joonas
>
I already understood what the function does. What I'm looking for asking is a 
specific example. What kind of resource might typically get attached in a 
real-world case? Yes, the search results show real world use on the API, but 
they shed little or no light on my general question.

Thanks,
Daniel