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Re: Adding many elements to a list
From: |
Pascal J. Bourguignon |
Subject: |
Re: Adding many elements to a list |
Date: |
Tue, 22 Sep 2009 14:37:15 +0200 |
User-agent: |
Gnus/5.101 (Gnus v5.10.10) Emacs/22.2 (gnu/linux) |
David Kastrup <dak@gnu.org> writes:
> 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.
You should write in assembler (what do I say, in binary!), because you
almost never need the flexibility that the bare push provide at
run-time, and at compilation time, it obfuscate what really happens,
including the possible performance impacts.
(disassemble (byte-compile (lambda (x) (push x *a*))))
-->
byte code:
args: (x)
0 varref x
1 varref *a*
2 cons
3 dup
4 varset *a*
5 return
See? There's a dup that's most often not used. Performance IMPACT!
--
__Pascal Bourguignon__
- Re: Adding many elements to a list, (continued)
- 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, 2009/09/22
- Re: Adding many elements to a list,
Pascal J. Bourguignon <=
- 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