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Re: Creating a simple state inspector for Mathematica

• To: mathgroup at smc.vnet.net
• Subject: [mg111857] Re: Creating a simple state inspector for Mathematica
• From: magma <maderri2 at gmail.com>
• Date: Sun, 15 Aug 2010 07:39:33 -0400 (EDT)
• References: <i45rgt$g5a$1@smc.vnet.net>

On Aug 14, 12:35 pm, "J. McKenzie Alexander" <ja... at lse.ac.uk> wrote:
> Hi,
>
> I'm trying to create a simple "state inspector" for Mathematica. Ideally,
> I'd like to have a dynamically updated list of all the symbols in Global`=
,
>  with the option of displaying their values, and the ability to Clear o=
r Remove symbols by clicking on a button. Now, I've managed to put together=
 something which *almost* does what I want, but it has a slight bug. What's=
 the bug? You can Clear a symbol by clicking on the button named "Clear", b=
ut clicking on the button named "Remove" generates an error. I don't unders=
tand why.

the command Remove is very nasty!
I would not recommend anybody using it in a program (that is a
sequence of steps running ).
One should only use it directly, that is typing it by hand, if at all.
The reason is that when you remove a symbol (say x), a sort of shadow
or ghost lingers in memory and is called Removed[x] and all
definitions (in Set, SetDelayed and elsewhere) are modified in such a
way that occurrences of x are replaced with Removed[x], practically
making them unusable by Mathematica again, even if you give x a value again.
So, I would simply NOT use Remove in your inspector.
Clear or ClearAll is enough for most reasonable things.