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[Axiom-developer] Re: init scripts

From: Vanuxem Grégory
Subject: [Axiom-developer] Re: init scripts
Date: Sat, 30 Jul 2005 21:49:26 +0200

Le samedi 30 juillet 2005 à 14:35 -0500, address@hidden a
écrit :
> Ok. Now I have a clue but it's subtle.
> You write this in your .axiom.input file:
> mrandom(x:Integer,v:Integer,z:Integer):ColumnMajorMatrix(SF) =
>  a:=matrix([[random(x)::SF for i in 1..y] for j in 
> 1..x])$ColumnMajorMatrix(SF)
>  a
> You can't see this function even though it appears to be defined. That's
> because Axiom is working in a new frame. 

Humm, I was thinking about that...

> When you start AXIOMsys you are running the interpreter talking directly
> to the terminal. So the .input file is actually talking to a frame
> at the top level. Your function is defined. 
> The .axiom.input file is read in a "frame" called "initial".
> AXIOMsys only uses the "initial" frame (although you can define and
> use new ones). A frame contains its own variables and function definitions.
> The "axiom" command does several things that AXIOMsys does not. In
> particular the axiom shell script starts up the 'sman' process which
> starts AXIOMsys (which reads the .axiom.input file) and then sman
> creates a new frame (usually a random lisp gensym name). In this new
> frame (created after .axiom.input is read) your mrandom function is
> not defined.
> To see this do:
>   AXIOMsys
>   mrandom(3,3,3)   -- compiles and runs the function
>   )quit
> Now do:
>   axiom
>   mrandom(3,3,3)   -- undefined function
>   )frame next
>   mrandom(3,3,3)   -- compiles and runs the function
>   )frame names     -- shows you all of the defined frames 
>   )quit
> So with the axiom shell script the process is:
>   axiom 
>     start sman                    (done by axiom shell script)
>       sman starts AXIOMsys        (done by sman)
>         create frame "initial"    (done by AXIOMsys)
>           read .axiom.input       (define your function here)
>         create frame "G00234"     (done by sman)
>           put up a command prompt (in frame G00234, no functions defined)
>         )frame next               (done by you)
>                         .... and now you're back in frame initial
>                         .... and your function is there
> So your function was read and it is defined. However the function got
> defined in the "initial" frame (because you defined it in the .axiom.input
> file) and is not known in the frame created by sman. The ")frame next"
> command will move you around the ring of frames. (See the hardcopy book
> on page 579).
> Tim

Thank you very much



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