Re: Multiple parallel environments

[ludo@gnu.org (Ludovic Courtès)]

Hello!

Peter Brett <peter@peter-b.co.uk> writes:

> ludo@gnu.org (Ludovic Courtès) writes:

[...]

>> What do you mean by "environment"?  All the global variables associated
>> with a given file in the editor?
>
> Sort of.  The whole of Guile's top level bindings at that point.  (The
> per-directory config is literally loaded as a Scheme script, so it
> could define and redefine functions and variables at will).

Then you are looking for Guile's nifty first-class modules.  The module
API is unfortunately lightly documented (info "(guile) Module System
Reflection").

>> What do you mean by "save"?  Serialize to a file the "environment"
>> associated with a file (or the difference compared to the initial
>> environment)?
>
> It doesn't need to be serialised -- I don't even need to be able to
> get a C pointer to it! -- it just needs to be "stashed" somewhere so
> that I can "rewind" Guile's toplevel bindings to that point at a later
> time.
>
> Essentially, I want each directory/"project" to be able to define its
> own functions, include its own modules etc. without stomping over
> another project that happens to be loaded into the application at the
> same time.

Easy!  :-)

What you would do is create one module for each file/project/directory:

  (define (make-per-file-module name)
    (let ((m (make-module)))
      (set-module-name! m name) ;; give the module an optional name
      (beautify-user-module! m) ;; populate the module with the
                                ;; default bindings
      m))

Then you create one such module for each file/directory/etc. and somehow
associate it with said file/directory/etc. (with an alist, a hash table,
or something similar).  When entering a file associated with that
module, you just have to make it current:

  (define (enter-file-buffer file)
    (set-current-module! (lookup-per-file-module file)))

And voilà!  :-)

Hope this helps,
Ludo'.