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RE: Releasing several Holds simultaneously

  • To: mathgroup at smc.vnet.net
  • Subject: [mg82272] RE: [mg82248] Releasing several Holds simultaneously
  • From: "Andrew Moylan" <andrew.j.moylan at gmail.com>
  • Date: Wed, 17 Oct 2007 03:46:48 -0400 (EDT)
  • References: <200710160727.DAA08807@smc.vnet.net> <CEB61950-22A8-40B0-8215-045B159914FD@mimuw.edu.pl>

Ah yes Hold->Identity was the other thing I tried. I guess I was put off by
then having a defined like this:

?a
>> Global`a
>> a:=Identity[1]



-----Original Message-----
From: Andrzej Kozlowski [mailto:akoz at mimuw.edu.pl] 
Sent: Tuesday, 16 October 2007 7:58 PM
To: Andrew Moylan
Cc: mathgroup at smc.vnet.net
Subject: [mg82272] Re: [mg82248] Releasing several Holds simultaneously

*This message was transferred with a trial version of CommuniGate(tm) Pro*

On 16 Oct 2007, at 16:27, Andrew Moylan wrote:

> Hold[a := Hold[1]]
>
> How can I release both of these Holds (and thus execute a:=1) 
> simultaneously?
>
> ReleaseHold[%] doesn't work; it evaluates a := Hold[1] before the 
> other hold is removed.
>
> % /. Hold[x_]:>x does the same thing, because /. only matches once per 
> part.
>
>
  Hold[a := Hold[1]] /. Hold -> Identity

a
1

Andrzej Kozlowski



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