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Re: [PATCH] (Updated) Run hook when variable is set


From: Richard Stallman
Subject: Re: [PATCH] (Updated) Run hook when variable is set
Date: Tue, 17 Feb 2015 18:07:02 -0500

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  > Saying there's only a global variable doesn't remove the absurdity of 
makunbound within the extent of a «let». Suppose foo is currently unbound. Then:
  > (defvar foo 0) ; Now foo is bound to 0
  > (let ((foo 1)) ; Now it's bound to 1
  >   (makunbound 'foo)) ; Now it's bound to unboundedness
  > ;; Now it's unbound from unboundedness, and thereby rebound to 0

That seems right to me.

  > You can't just say that makunbound in that case unbinds foo,
  > because then the question arises, from what is foo unbound when
  > the let-binding form exits? If foo were already unbound by
  > makunbound, then there would be nothing left to unbind it from
  > when «let» exits.

The word "unbound" is being used in an ambiguous fashion, but once you
see past that, there is nothing strange about what's really going on.

Maybe we should change terminology to get rid of the ambiguity.
The name 'makunbound' is the cause of it, but that is hard to change now.
We could at least explain it better.

-- 
Dr Richard Stallman
President, Free Software Foundation
51 Franklin St
Boston MA 02110
USA
www.fsf.org  www.gnu.org
Skype: No way! See stallman.org/skype.html.




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