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From: "Davis Herring" <herring@lanl.gov>
To: "Daniel Colascione" <daniel@censorshipresearch.org>
Cc: Emacs development discussions <emacs-devel@gnu.org>
Subject: Re: Why isn't the string returned by symbol-name read-only?
Date: Sat, 23 Jan 2010 17:12:17 -0800 (PST)	[thread overview]
Message-ID: <15016.128.165.0.81.1264295537.squirrel@webmail.lanl.gov> (raw)
In-Reply-To: <4B5B6250.1080108@censorshipresearch.org>

> That returns in an error when you try to evaluate it. The object
> returned by (symbol-name 'car) must have some read-only bit set.
>
> Why isn't that bit set for *all* symbol names?

It's set for that string not because `car' is too important to be changed,
but because it was created before Emacs was dumped.  (Of course, it is
created that early because it is important.)  Making such strings
read-only saves the time in checking whether they might need
garbage-collection later.  So it's purely an optimization; it's not meant
to protect anything.

Davis

-- 
This product is sold by volume, not by mass.  If it appears too dense or
too sparse, it is because mass-energy conversion has occurred during
shipping.




  parent reply	other threads:[~2010-01-24  1:12 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-01-23 20:55 Why isn't the string returned by symbol-name read-only? Daniel Colascione
2010-01-23 21:53 ` Chong Yidong
2010-01-24  0:33 ` alin.s
2010-01-24  9:48   ` Thien-Thi Nguyen
2010-01-24  1:12 ` Davis Herring [this message]
2010-01-24 11:19   ` alin.s
2010-01-25  3:08 ` Stefan Monnier

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