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Re: iterating over a list while removing elements
From: |
lee |
Subject: |
Re: iterating over a list while removing elements |
Date: |
Thu, 20 Mar 2014 17:02:26 +0100 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/24.3.50 (gnu/linux) |
Stefan <monnier@iro.umontreal.ca> writes:
>> (string-match "\\.$" dots)
>> (string-match "\\.\\.$" dots)))
>
> You meant
>
> (string-match "\\.\\'" dots)
> (string-match "\\.\\.\\'" dots)))
Hm, what`s the difference?
>> Surprisingly, this /appears/ to work. Can I take that for granted, or
>> is this a stupid thing to do? It`s like someone pulling the chair
>> you`re about to sit on from underneath you ...
>
> This is undocumented, so better not rely on the details of the behavior.
> You can rely on the fact that dolist will behave sanely, tho: it should
> not go berzerk, it should go through at least all elements still
> remaining in the list, and at most all elements that have been in
> the list.
>
> But you should better not assume that dolist will skip the "entry" you
> just removed. E.g. you could do the following, which should be somewhat
> faster (since `delete' is O(n)):
Duplicating the list is an approach I used at other places, and I was
wondering if there`s some way to do it without duplication. The list
can be fairly large, and I`m using several, so saving some memory would
be nice, even if it usually doesn`t really matter.
Anyway, redundancy through `delete' isn`t good, letting aside that it
may yield unexpected results.
> (defun multisearch-make-files-list (directory)
> "Return a list of files in DIRECTORY, with directory references
> and directories removed."
> (let ((files-list (directory-files directory t))
> (newlist '()))
Why not (newlist nil)?
I`ve got it working nicely now, you can find the whole thing at
https://github.com/lee-/emacs/tree/master/multisearch
--
Knowledge is volatile and fluid. Software is power.