[plt-scheme] environment variables (i.e. getenv)

I just noticed that you have created a package for this,
http://planet.plt-scheme.org/300/#get-environment.plt

On 3/23/07, Daniel Yoo <dyoo at cs.wpi.edu> wrote:
>
>
> On Fri, 23 Mar 2007, Andrew Gwozdziewycz wrote:
>
> > In scheme48 there is a function that returns an association list of all
> > the environment variables, environment->alist.
> >
> > Is there something similar in MzLib? I've only come up with references
> > to getenv in my searching, but that only returns one variable or #f. Any
> > help appreciated.
>
>
> Hi Andrew,
>
> This might not be completely right yet, but here's something that should
> help, using the Foreign Function Interface (FFI):
>
> ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
> (module environ-vars mzscheme
>    (require (lib "foreign.ss"))
>    (unsafe!)
>    (provide get-environ)
>
>    (define lib (ffi-lib #f))
>
>    ;; get-environ: -> (listof byte-string)
>    ;; Returns a list of byte strings.  Each byte string will be
>    ;; in the form "key=value".
>    (define (get-environ)
>      (let ([byte-ptr (get-ffi-obj "environ" lib _pointer)])
>        (let loop ([results '()]
>                   [i 0])
>          (let ([next-elt (ptr-ref byte-ptr _bytes/eof i)])
>            (cond
>              [(eof-object? next-elt) (reverse! results)]
>              [else
>               (loop (cons next-elt results) (add1 i))]))))))
> ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
>
>
> This module should provide access to the environ byte strings, so that you
> can later figure out all the environment names:
>
> ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
> > (map (lambda (b) (car (regexp-match #rx"^[^=]+" b))) (get-environ))
> (#"SSH_AGENT_PID"
>   #"SHELL"
>   #"GTK_RC_FILES"
>   #"OLDPWD"
>   #"USER"
>   #"GNOME_KEYRING_SOCKET"
>   #"SSH_AUTH_SOCK"
>   #"SESSION_MANAGER"
>   #"USERNAME"
>   #"DESKTOP_SESSION"
>   #"PATH"
>   #"GDM_XSERVER_LOCATION"
>   #"PWD"
>   #"JAVA_HOME"
>   #"LANG"
>   #"GDMSESSION"
>   #"HOME"
>   #"SHLVL"
>   #"LANGUAGE"
>   #"GNOME_DESKTOP_SESSION_ID"
>   #"LOGNAME"
>   #"DBUS_SESSION_BUS_ADDRESS"
>   #"DISPLAY"
>   #"XAUTHORITY")
> ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
>
>
> Best of wishes!
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>



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