Please help me think of an example where immutable tuples are
essential.
It seems that everywhere a tuple is used one could just as easily use
a list instead.
chris
27  1665  se******@spawar .navy.mil wrote:
Please help me think of an example where immutable tuples are
essential.
When used as dictionary keys (also everywhere else where they must
be in a constant order).
Yes, this *is* used in practice.
Regards,
Björn
--
BOFH excuse #14:
sounds like a Windows problem, try calling Microsoft support
On Apr 20, 2:06 pm, "seber...@spawa r.navy.mil"
<seber...@spawa r.navy.milwrote :
Please help me think of an example where immutable tuples are
essential.
It seems that everywhere a tuple is used one could just as easily use
a list instead.
chris
I don't remember exactly where I read about it, but Guido said once
that tuples are being kept mainly for historical reasons.
This is what Python uses internally from the beginning and it's just
an implementation detail that makes sense in some contexts.
Although I guess you can ignore them and use only lists instead if you
want..
luis
Luis M. González wrote:
I don't remember exactly where I read about it, but Guido said
once that tuples are being kept mainly for historical reasons.
Weren't tuples added when lists already existed?
Regards,
Björn
--
BOFH excuse #101:
Collapsed Backbone
Iou need only consider having cartesian coordinate sets as the keys
for an example. A 2 dimensional list might be overly expensive if your
coordinates span a large area but are relatively sparse.
En Fri, 20 Apr 2007 15:28:51 -0300, Bjoern Schliessmann
<us************ **************@ spamgourmet.com escribió:
Luis M. González wrote:
>I don't remember exactly where I read about it, but Guido said
once that tuples are being kept mainly for historical reasons.
Weren't tuples added when lists already existed?
Both listobject.c and tupleobject.c appear to had been checked in at the
same time:
Revision 2167 - (view) (download) (as text) - [select for diffs]
Added Sun Oct 14 12:07:46 1990 UTC (16 years, 6 months ago) by guido
File length: 4965 byte(s)
Initial revision
And that's before the earliest tagged release I could find on svn, Python
0.98
--
Gabriel Genellina
On Apr 20, 3:28 pm, Bjoern Schliessmann <usenet-
mail-0306.20.chr0n.. .@spamgourmet.c omwrote:
Luis M. González wrote:
I don't remember exactly where I read about it, but Guido said
once that tuples are being kept mainly for historical reasons.
Weren't tuples added when lists already existed?
Regards,
Björn
--
BOFH excuse #101:
Collapsed Backbone
I tried googling for these comments, but I couldn't find them.
Perhaps I never read them and it was just my imagination...
Anyway, I suggest reading this chapter of "Dive into Python" for a
good explanation of the differences between tuples and lists: http://diveintopython.org/native_data_types/tuples.html
The article explains that, amongst other things, tuples are faster
than lists, so if you are working with constant values (inmutables)
they are more indicated than lists.
luis
On Apr 20, 6:09 pm, Bjoern Schliessmann <usenet-
mail-0306.20.chr0n.. .@spamgourmet.c omwrote:
seber...@spawar .navy.mil wrote:
Please help me think of an example where immutable tuples are
essential.
When used as dictionary keys (also everywhere else where they must
be in a constant order).
Yes, this *is* used in practice.
Yup - using tuples as dictionary keys is very common.
Fuzzyman http://www.voidspace.org.uk/python/index.shtml
Regards,
Björn
--
BOFH excuse #14:
sounds like a Windows problem, try calling Microsoft support
The article explains that, amongst other things, tuples are faster
than lists, so if you are working with constant values (inmutables)
they are more indicated than lists.
Thanks. I thought Python's design wasn't so concerned with
optimizations.
Adding a new type "just" for optimization reasons seems perhaps
unnecessary. I could be wrong.
On Apr 21, 7:09 am, Luis M. González <luis...@gmail. comwrote:
On Apr 20, 3:28 pm, Bjoern Schliessmann <usenet-
mail-0306.20.chr0n.. .@spamgourmet.c omwrote:
Luis M. González wrote:
I don't remember exactly where I read about it, but Guido said
once that tuples are being kept mainly for historical reasons.
Weren't tuples added when lists already existed?
Regards,
Björn
--
BOFH excuse #101:
Collapsed Backbone
I tried googling for these comments, but I couldn't find them.
Perhaps I never read them and it was just my imagination...
Anyway, I suggest reading this chapter of "Dive into Python" for a
good explanation of the differences between tuples and lists:http://diveintopython.org/native_data_types/tuples.html
The article explains that, amongst other things, tuples are faster
than lists, so if you are working with constant values (inmutables)
they are more indicated than lists.
One inessential but very useful thing about tuples when you have a lot
of them is that they are allocated the minimum possible amount of
memory. OTOH lists are created with some slack so that appending etc
can avoid taking quadratic time. This thread has been closed and replies have been disabled. Please start a new discussion. Similar topics | |
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--
--
Every sufficiently advanced magic is indistinguishable from technology
- Arthur C Anticlarke
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Consider the following tuples:
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--
\ "Love is the triumph of imagination over intelligence." -- |
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