Re: about scoping in modules
- To: mathgroup at smc.vnet.net
- Subject: [mg85795] Re: about scoping in modules
- From: David Bailey <dave at Remove_Thisdbailey.co.uk>
- Date: Fri, 22 Feb 2008 07:23:31 -0500 (EST)
- References: <fpkvqk$hrr$1@smc.vnet.net>
P_ter wrote:
> Hello,
> in the next two modules I would like that the inner module uses a variable from the outer module.
> mfb[oneObj_] := Module[{ttmp = oneObj},AppendTo[ global2mfb, ttmp]]
> mfa[e_] := Module[{global2mfb = e, t = 3},mfb[t] ]
> mfa[{2,3}] gives a message that global2mfb is not a variable with a value, so it can not be changed.
> It means I do not understand the concept of module in Mathematica. My questions are:
> 1. why does it go wrong?
> 2. how can I realize what I want?
> with friendly greetings,
> P_ter
>
Well, despite its name, global2mfb is local to the Module in which it
appears - so using it elsewhere refers to a global variable of the same
name with no value - hence the diagnostic. This is the purpose of Module
- to stop one use of a variable clashing with another.
Take the assignment global2mfb=e outside the list of local
initialisations, and I think you will get what you want.
David Bailey
http://www.dbaileyconsultancy.co.uk