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Re: Basic questions about elisp


From: Lennart Borgman
Subject: Re: Basic questions about elisp
Date: Thu, 5 Nov 2009 13:44:25 +0100

On Thu, Nov 5, 2009 at 1:07 PM, Francis Moreau <address@hidden> wrote:
> On Nov 5, 12:50 pm, Lennart Borgman <address@hidden> wrote:
>> On Thu, Nov 5, 2009 at 12:13 PM, Francis Moreau <address@hidden> wrote:
>> > Hello,
>>
>> > I'm trying to learn elisp and have a couple of basic questions.
>>
>> > I'm iterating over a list using dotimes, but in the body of dotimes,
>> > the list can mutate. For example I have:
>>
>> >  (dolist (elt lst)
>> >    ;; some codes
>> >    (nconc lst '(2)))
>>
>> > This adds/appends a new element to 'lst' list. It looks like 'dotimes'
>> > doesn't like it.
>>
>> > So I eventually wrote it like this
>>
>> >    (setq i 0)
>> >    (while (< i (length lst))
>> >          ;; some codes
>> >          (x-nconc lst '(2))))
>> >      (setq i (1+ i)))
>>
>> > which is a bit ugly, is there another way to do that ?
>>
>> It is much easier to answer if you define exactly what you want to do
>> when lst grows.
>
> I'd like to iterate over all elements of the list even if the element
> are appended during the loop execution.
>
> For example if the list is (1 2) before entering in the loop and then
> during the first iteration the code append '3' to the list so it
> becomes (1 2 3), I'd like the loop to iterate over the '3' element as
> well. 'dotimes' doesn't seem to do that.


Can't you just add the new elements to the end of the list and in each
iteration check if there are anything left in the tail to handle?




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