Re: scm_* API extension? [was] scm_* API question

[Han-Wen Nienhuys]

address@hidden writes:
> 
> What is an 'interpreter'?  What do multiple instances of the
> interpreter have in common, what is specific to each instance?  I
> think that once you know what you want from multiple interpreters, you
> can implement them easily with the features we already have.  Or with
> fork.

What I want is a way to encapsulate state changes; modules give a nice
way to deal with naming variables, but not with their values. When I
have two lilypond files, one doing

f1.ly

         #(set! global-foo-option #t) ;; default  = #f
         \score  {\notes { .. } }

f2.ly

        \score { \notes { ..other notes.. } }

What really happens during execution depends on the order of
execution: if you do

        lilypond f1 f2

then f2 is processed with global-foo-option set to #t. If you change
the order, then f2 is processed with global-foo-option set to #f.

It would be nice if we could have some kind of copy-on-write system
for variables, so that I can reset the state of the variables before
processing each new file.

[disclaimer, I know nothing of advanced Scheme techniques, I might be
missing some basic idiom here completely.]

-- 

Han-Wen Nienhuys   |   address@hidden    | http://www.cs.uu.nl/~hanwen/