[cffi-devel] New foreign library interface

[Luís Oliveira]

On 2006-jan-05, at 09:28, James Bielman wrote:
> The only thing I might like to change here is that :alternatives  
> seems a
> little verbose to me.  Would it be confusing to just re-use :or for
> this?  Or just a list with no leading keyword symbol?

Yeah, your original suggestion was to use just a list, but I added a  
symbol to more easily differenciate it from the other possible list:  
(:framework foo). I think I'll go with the :OR suggestion, since it's  
probably more readable than just a list too.


>>     b) A pathname, in which case CFFI doesn't try to find it and  
>> simply
>>        passes its namestring to load-foreign-library.
>
> I'm not sure I understand why the behavior for a pathname would be
> different than that of a namestring.  If the pathname was relative,
> wouldn't it make sense to perform the same search if
> LOAD-FOREIGN-LIBRARY can't find it?

Right, makes sense.


[about find-foreign-library and friends]
> Besides, it's not clear to me how we can perform the same search  
> that a
> 'dlopen' would do without either trying to duplicate it, or trying it
> load it.

> For scenario 2, if the user doesn't want to load the library from the
> standard locations, he will need a custom search strategy for locating
> the library anyway, so whatever function we supply isn't going to cut
> it, I think.

Oh yes, find-foreign-library only searches in the directories that  
are passed to it as an argument (usually cffi:*foreign-library- 
directories*) not in the places that ldopen would search. But I  
suppose that could help in such custom search strategy anyway?

Well, find-foreign-library is probably a misnomer. It's more of a  
find-file-in-a-list-of-directories, really.


>> Also, maybe a functional interface to use-foreign-library could be
>> useful?
>
> How about making LOAD-FOREIGN-LIBRARY load a "logical" library defined
> with DEFINE-FOREIGN-LIBRARY if passed a symbol?

While we're at it, I suppose that it could take a (:framework "foo")  
pair as well as a list of alternatives: (:or "lib1.so" "lib2.so")?  
And have it search in cffi:*foreign-library-directories* too.

Ie. load-foreign-library should handle its argument exactly the same  
way an "element" in define-foreign-library is handled. Sounds intuitive.

-- 
Luís Oliveira
http://student.dei.uc.pt/~lmoliv/
Equipa Portuguesa do Translation Project
http://www.iro.umontreal.ca/translation/registry.cgi?team=pt