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RE: Context

• To: mathgroup at smc.vnet.net
• Subject: [mg70985] RE: [mg70956] Context
• From: "Virgilio, Vincent - SSD" <Vincent.Virgilio at itt.com>
• Date: Fri, 3 Nov 2006 01:39:40 -0500 (EST)

Likely the current context doesn't change until the end of the current
expression (similar to the play between side-effects and sequence points
in C/C++).

Below, a CompoundExpression[] contains a Begin[].  I think the Begin[]
will not affect anything in that CompoundExpression[]. So Mathematica
creates t in Global` rather than x`, which you see.

I don't know how to draw a line between parsing and execution in
Mathematica. Perhaps it could be done in terms of the documented
evaluation process. There's been some talk on this lately, I think about
Format[]. Anyone care to elaborate?

Vince Virgilio


-----Original Message-----
From: dh [mailto:dh at metrohm.ch] 
To: mathgroup at smc.vnet.net
Subject: [mg70985] [mg70956] Context


Hello,

consider:

fun[x_]:=( Begin[x];

       Print[t];

       End[];

       );

according to the manual one would think that the variable t in context x


is printed. However, this is wrong! What is printed is Global`t. 

Therefore, the context to which a symbol belongs is determined during 

parsing and NOT execution.

Can anybode give more insight and strict rules for this quirck?

Daniel


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    • From: Sseziwa Mukasa <mukasa@jeol.com>