[asdf-devel] loading platform-dependent code

[Tamas Papp]

Hi,

I am the author of the cl-cairo2 library.  Cairo itself is a graphics
library, and my library provides a Lisp interface.

Some of the features (eg drawing in X11, Windows or Quartz) are
platform dependent.  Currently, the approach of cl-cairo2 is to
provide extra system definitions for these, eg an X11 user would load
the systems cl-cairo2 and cl-cairo2-x11 manually.  I am wondering if
there is a better way to do platform-dependent loading.

The solution I was thinking of was to try loading the platform
dependent shared C libraries using CFFI, and set some flag (or push
something to *features*) if they succeed, but if they fail, capture
the condition with handler-case and just proceed with a warning.  Then
I could load platform-dependent code conditionally on this --- but I
don't know how to do that in ASDF.

Please tell me what is the "right way" to do these things (ie stuff
that I put in features).  Examples of libraries that load
platform-dependent code conditionally with ASDF would also help.

Thanks,

Tamas