[Cairo] Re: Text APIs round 2

[Keith Packard]

Around 14 o'clock on Aug 14, graydon hoare wrote:

> the point I was making is that some users of cairo will in some cases
> *certainly* need to use the native font API, so we're going to be
> caching a pointer to the native structure anyways. that makes for one
> more pointer I have to keep in my struct and one more thing I have to
> keep in sync with cairo any time a font call is made. 

I was thinking that applications would instead save *only* the native 
pointer and convert to the generic type when setting it into the rendering 
context.  Saving two pointers is clearly a bad idea; as I said, if you 
think that's going to be necessary, I don't see any advantage to having 
native types when the insides are completely virtual in any case if there 
isn't any effective typechecking (the existance of a back conversion 
function obviates any typechecking in practice).

> I'd prefer to just ask cairo at runtime, but I can live with it either way.

I'm not sure that makes sense -- you can't do anything with the native 
datatypes except pass them to native functions, so you're going to have to 
do compile-time checking in any case.

-keith