[Python-Dev] python-dev Summary for 10-16-2003 through 11-15-2003[draft]

Raymond Hettinger python at rcn.com
Sun Nov 23 19:27:29 EST 2003

> If you ever wanted to have the power of list comprehensions but
> the overhead of generating the entire list you have Peter Norvig
> initially and then what seems like the rest of the world for generator
> expressions.

[possibly mangled sentence doesn't make sense]

> After the addition of the 'key' argument to list.sort(), people began
> clamor for list.sort() to return self.  Guido refused to do give in,
> a compromise was reached.  'list' now has a class method named
>   Pass it a list and it will return a *copy* of that list sorted.

What makes a class method so attractive is that the argument need not be
a list, any iterable will do.  The return value *is* of course a list.

By returning a list instead of None, list.sorted() can be used as an
expression instead of a statement.  This makes it possible to use it as
an argument in a function call or as the iterable in a for-loop::

    # iterate over a dictionary sorted by key
    for key, value in list.sorted(mydict.iteritems()):

> As an interim solution, itertools grew a new function: tee.  It takes
> an iterable and returns two iterators which independently iterate over
> the iterable.

[replace] two
[with] two or more

> The point that operator.isMappingType is kind of broken came up.  Both
> Alex and Raymond Hettinger would not mind seeing it disappear.  No one
> objected.  It is still in CVS at the moment, but I would not count on
> necessarily sticking around.

["It's not quite dead yet" ;-)  Actually, there may be a way to
partially fix-it so that it won't be totally useless].

> There was a new built-in named reversed(), and all rejoiced.

[And much flogging of the person who proposed it]

> Straight from the function's doc string: "reverse iterator over values
> of the sequence".  `PEP 322`_ has the relevant details on this toy.

[Replace] toy
[With] major technological innovation of the first order
[Or just] builtin.

> Sets now at blazing C speeds!

[Looks like a certain parroteer will soon by eating pie!]

Another fine summary.
Thanks for the good work.


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