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Re: Adding many elements to a list
From: |
David Kastrup |
Subject: |
Re: Adding many elements to a list |
Date: |
Tue, 22 Sep 2009 14:16:28 +0200 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/23.1.50 (gnu/linux) |
pjb@informatimago.com (Pascal J. Bourguignon) writes:
> David Kastrup <dak@gnu.org> writes:
>
>> pjb@anevia.com (Pascal J. Bourguignon) writes:
>>
>>> David Kastrup <dak@gnu.org> writes:
>>>
>>>> pjb@anevia.com (Pascal J. Bourguignon) writes:
>>>>
>>>>> David Kastrup <dak@gnu.org> writes:
>>>>>
>>>>>> pjb@informatimago.com (Pascal J. Bourguignon) writes:
>>>>>>
>>>>>>> So better use (require 'cl) (push new-item list)
>>>>>>> or (cons new-item list)
>>>>>>> or (append (list new-items...) list)
>>>>>>
>>>>>> (require 'cl) is quite unnecessary for all of the mentioned
>>>>>> alternatives.
>>
>> Try emacs -Q. Just because you choose to load some library
>> overloading the default operators does not mean that other people
>> should do the same when Emacs will provide those operators by
>> default, with better performance.
>
> Ah! :-)
>
> The cl package wouldn't be provided if the default had any performance
> at all...
>
>
> (defvar *a* (cons nil nil))
> (push 1 (car *a*))
Well, consult its doc string for what it does and doesn't. It's
basically the same issue as with setf/setq: the cl version of push does
a number of different things depending on a vague concept "location".
But you almost never need this sort of flexibility at runtime, and at
compile time, it obfuscates what actually happens, including the
possible performance impacts.
--
David Kastrup
- Adding many elements to a list, Nordlöw, 2009/09/18
- Re: Adding many elements to a list, Pascal J. Bourguignon, 2009/09/18
- Re: Adding many elements to a list, David Kastrup, 2009/09/18
- Re: Adding many elements to a list, Pascal J. Bourguignon, 2009/09/19
- Re: Adding many elements to a list, David Kastrup, 2009/09/18
- Re: Adding many elements to a list, Thierry Volpiatto, 2009/09/18
- Re: Adding many elements to a list, Pascal J. Bourguignon, 2009/09/19
- Re: Adding many elements to a list, Andreas Politz, 2009/09/19
- Re: Adding many elements to a list, David Kastrup, 2009/09/22
- Re: Adding many elements to a list, Pascal J. Bourguignon, 2009/09/22
- Re: Adding many elements to a list,
David Kastrup <=
- Re: Adding many elements to a list, Pascal J. Bourguignon, 2009/09/22
- Re: Adding many elements to a list, David Kastrup, 2009/09/22
- Re: Adding many elements to a list, Samuel Wales, 2009/09/28
Re: Adding many elements to a list, David Kastrup, 2009/09/18