Re: Interpreter Sessions (Newbie)

[Clinton Ebadi]

On Saturday 22 February 2003 12:03, Pedro Ortega wrote:
> 1. Given an user id, create (if it doesn't exist) or
>    restore the environment (using a database or another
>    persistent storage media).

You can do this with modules:

;;; (make-module size uses-list)
(define userid-module (make-module 1021 (list (resolve-module 
'(guile-user)))))

Now you have a module that has access to all the symbols from guile-user (you 
can add other modules to the uses-list, just use resolve-module to resolve 
the module from the name).

You can then pass userid-module as the second argument to eval or you can do 
things like:

(module-define! userid-module 'foo 5) ; foo now has the value 5 in 
userid-module

> 2. Execute the Scheme code with the environment, in order
>    to get the response string.

(eval "expression" userid-module)

Or I think you may be able to have different module set for each thread so you 
could give each user their own thread and do (set-current-module 
userid-module) in that thread (I'm not entirely sure because I don't use 
threads).

> 4. Save the updated environment.

You can't do this right now, although I could add support for serializing 
modules to my hacked together object serializer 
(http://unknownlamer.org/files/temp/serialize.scm) which I will be merging 
back into Guile-Web soon.

-- 
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