Antoon Pardon wrote:
On Sun, Mar 13, 2011 at 12:59:55PM +0000, Steven D'Aprano wrote:
The removal of cmp from the sort method of lists is probably the most
disliked change in Python 3. On the python-dev mailing list at the
moment, Guido is considering whether or not it was a mistake.
If anyone has any use-cases for sorting with a comparison function that
either can't be written using a key function, or that perform really
badly when done so, this would be a good time to speak up.
How about a list of tuples where you want them sorted first item in ascending
order en second item in descending order.
Greetings,
Not sure here, but thought you folks might want to have another
viewpoint from someone who is maybe not so close to the trees as to be
able to comment effectively on the forest.
Many of you (Guido included) have lost significant sight of a
critical object oriented philosophical pillar (but not all of you, thank
goodness). To cut right to the heart of it--- NEVER change an advertised
interface. Change the implementation to your little hearts desire, but
never alter an advertised interface (code is based on it, books are
based on it, tutorials are based on it, college comp sci courses are
based on it... etc). If cmp parm is utilized and is helpful or perceived
as useful and existing code requires it then for crying out loud leave
it alone. I think your overall worship of Guido as Python King has left
many of you with nobbled thinking.
On the other hand, this debate and constant bickering is a serious
rehash of an ancient discussion without any new points--- irritating.
Take a look at issue 1771 http://bugs.python.org/issue1771
particularly msg #s 95975 and 95982.... but no, read the whole
thing.... it is very clear that Guido wants to restructure the python
language for consistency and elegance (and who can blame him?). He makes
some very good arguments for the justification of removing the cmp
keyword from list.sort() and builtin.sorted()/ but, that is not the
point... he is breaking a fundamental law of object oriented
programming... don't break and advertised interface (particularly if it
is useful and people are actually making use of it!).
This is insane folks.
Python is one of the most elegant OO languages to gain popular
appeal and wide-spread use. This sad broken move from 2.x to 3.x has the
potential of ruining the language for everyone. Many of us dropped JAVA
(compile once debug everywhere) because it is complicated, a pita to
use, slow, and actually doesn't port too well on any platform... and
here we go again with python. How do the developers of python ever
expect folks to be able to make use of the language into the future when
every time we turn around the interface is broken or being debated in
flux? Many of us want to use the new 3.2+ version, but no one is going
to ship it pre-installed (probably for many years) because of this
issue. There is no way to easily migrate, nor backport, and everyone is
going to be forced to develop code (and have to maintain code) on two
distinct branches (for many years to come). I suspect that people are
just going to stick with back versions for a long time.
We need to get a grip on this, people.
Guido does not need a use case; he just needs to restore the
interface that everyone expects. Put up a message to start to use key=
instead, and plan deprecation for something like five years out... this
just seems like such a no-brainer to me. But then, maybe its just that
I'm too inexperienced to know any better. <sigh>
In the mean time... I'm playing around with 3.2 and really liking
it... hoping that the world will actually be using it someday.
Kind regards,
m harris
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