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named pattern variable scoped as global, should be local

• To: mathgroup at smc.vnet.net
• Subject: [mg56696] named pattern variable scoped as global, should be local
• From: leenewman at gmail.com
• Date: Wed, 4 May 2005 00:33:07 -0400 (EDT)
• Sender: owner-wri-mathgroup at wolfram.com

When using a named pattern variable within a module, it should be
scoped locally within the pattern.  However, this does not seem to work
as advertised.  For example, shouldn't the pattern variable x in the
statements below be local to the pattern?  Does anyone know whether
this is a bug, or whether I am just missing something about the usage
of variables in patterns/condition constructs?

(* this returns 14! *)
x = 7;
Module[{x},{1, 2, 3} /. x_ -> 2x];

(* this returns {2,4,6}, assuming q is not globally defined. *)
Remove[q];
Module[{q},{1, 2, 3} /. q_ -> 2q];


Lee

• Follow-Ups:
  • Re: named pattern variable scoped as global, should be local
    • From: DrBob <drbob@bigfoot.com>
  • Re: named pattern variable scoped as global, should be local
    • From: Andrzej Kozlowski <akoz@mimuw.edu.pl>