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From: pjb@informatimago.com (Pascal J. Bourguignon)
To: help-gnu-emacs@gnu.org
Subject: Re: Length of obarray vectors
Date: Fri, 06 Nov 2009 13:03:59 +0100	[thread overview]
Message-ID: <87pr7vdfm8.fsf@galatea.local> (raw)
In-Reply-To: 87y6mjdht5.fsf@galatea.local

pjb@informatimago.com (Pascal J. Bourguignon) writes:

> Nordlöw <per.nordlow@gmail.com> writes:
>
>> On Nov 6, 11:18 am, Nordlöw <per.nord...@gmail.com> wrote:
>>> What length should I use when I create a vector that will act as an
>>> obarray?
>>> My suggestion: The smallest prime larger than the number of symbols
>>> that should be interned?
>>> If this is correct why does (length obarray) give such a small number,
>>> 15
>>>
>>> Thanks,
>>> Nordlöw
>>
>> It should be 1511, not 15.
>>
>> Forgot one thing: My guess: Is it a trade-off of performance (big
>> length) and memory usage (small length)?
>
> The reason is that obarrays are not arrays, but trees. You're watching
> only the root of the tree.

Sorry, not trees, but kinds of hash-tables.

-- 
__Pascal Bourguignon__


      reply	other threads:[~2009-11-06 12:03 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-11-06 10:18 Length of obarray vectors Nordlöw
2009-11-06 10:20 ` Nordlöw
2009-11-06 11:16   ` Pascal J. Bourguignon
2009-11-06 12:03     ` Pascal J. Bourguignon [this message]

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