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Re: How does Clear["Global`*"] work?

• To: mathgroup at smc.vnet.net
• Subject: [mg120822] Re: How does Clear["Global`*"] work?
• From: David Bailey <dave at removedbailey.co.uk>
• Date: Thu, 11 Aug 2011 07:55:33 -0400 (EDT)
• Delivered-to: l-mathgroup@mail-archive0.wolfram.com
• References: <j206b9$71e$1@smc.vnet.net>

On 11/08/2011 10:11, Themis Matsoukas wrote:
> According to http://reference.wolfram.com/mathematica/howto/ClearMyDefinitions.html, Clear["Global`*"] clears all the definitions made during the current Mathematica session. However,
>
> a = 1;
> Clear["Global`*"]
> a
>
> 1
>
> How is Clear["Global`*"] supposed to work?
>
> Thanks
>

This looks to me like a bug introduced at 8.0. The command Clear["Global`*"]
seems to work at 7.0, but at 8.0 it generates an error message:

Clear::wrsym: Symbol TimeStamp is Protected. >>


This seems to be because at 8.0, Wolfram have accidentally introduced a 
protected symbol into the Global` context:

In[9]:= Context[TimeStamp]

Out[9]= "Global`"

In[10]:= Attributes[TimeStamp]

Out[10]= {Protected}

Presumably this aborts the Clear command part way through (though of 
course many commands don't give up if they hit an error).

David Bailey
http://www.dbaileyconsultancy.co.uk

• Follow-Ups:
  • Re: work?
    • From: Murray Eisenberg <murray@math.umass.edu>