Re: Passing lambda bindings to C for use as callback

[Marc Singer]

On Mon, Nov 25, 2002 at 06:45:45PM -0800, Marc Singer wrote:
> ...works for a while and then the gh_apply fails stating that the
> callback function is missing.  My guess is that this callback, an
> anonymous lambda binding, is being garbage collected.  
> 
> I've found a reference to this problem and some solution being made
> for tcl.  Will someone share with me either the solution or a place to
> find it?

I found the answer by browsing an old CVS archive of the guile code.
Turned out to be quite easy.

 1) On startup, I register a hook using scm_c_hook_add () for
    scm_before_sweep_c_hook.

 2) I store SCMs for active callbacks in one datastructure
 
 3) When the hook procedure executes, it calls scm_gc_mark on each of
    the callback SCMs.

Cake.