[Jscheme-user] Re: loading additional code in servlet?

[Ken A. <kan...@bb...>]

OK, i like your approach of everyone sharing the same environment.
This is what the lisp machine did, though there was typically only one user at a time, though many processes with no user/kernel distinction.  You could take down a Lisp Machine by typing (setq current-process nil)

Luckily, you could use set! to redefine define.

Maybe you can make a game for your students out of this - write your servlet so what people do to the global environment won't bother it.  It might motiviate a good discussion about modularity and objects.

k

At 04:36 PM 8/10/2004 -0400, Timothy John Hickey wrote:

>On Aug 10, 2004, at 3:14 PM, Ken Anderson wrote:
>
>>Tim,
>>Your documentation mentions that a init.scm file is loaded the first time a .servlet is executed.
>> How should a servlet that needs to load code do it so it only happens once?
>One way is to use the (use-module "FILE.scm") command
>but we need to make a (reload-module "FILE.scm") command that can be used in development....
>
>>
>>Also, since all servlets run in the same environment, won't your students potentially have name conflicts, at least potentially?
>This is true, but I view it as a feature and not a bug.
>
>The idea is to have the student's append their initials or login id to all their globally defined names
>(e.g.   (define (tjh-webpage TITLE CSS BODY) ......)    )
>then the students can load each others code and use each other's procedures ...
>
>We could also have students use the
>      (use-module "FILE.scm" 'import 'all "PREFIX:")
>or (reload-module "FILE.scm" 'import 'all "PREFIX:")
>approach to load in their code with a prefix..... This keeps the FILE.scm code simple
>and still allows the libraries to be used without much interference...
>
>This can be used to encourage a community of reuse. Student's in the summer course
>thought it was very cool that they could all use everyone else procedures ....
>
>I do need a way for them to reset the primitives, because last summer someone
>wrote a servlet that started with
>    (set! define 5)
>which wiped out the real defintion of define!!
>
>Another possibility would be to create a global hashtable H of jscheme.JScheme instances
>and have a  macro that looked up the SchemeEvaluator in which to evaluate the servlet...
>
>For example,
>
>(use-context
>   "tjh"
>
>  (use-module "mydefs.scm" 'import 'all)
>  ...
>  (servlet  (a b c)
>     BODY
>   )
>)
>
>would lookup the context (a jscheme.JScheme. instance)
>with key "tjh" (or create one if it doesn't exist), and then
>evaluate the servlet in that context. Does this seem like
>a reasonable approach??
>
>---Tim---
>
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>>
>>k