Comments on: Recent Python annoyances

By: Rob

Rob — Fri, 14 Nov 2008 19:24:18 +0000

The object assignment behavior isn’t wrong, just your understanding of it is. An assignment assigns a name to an object and does nothing else. IOW, assignments only modify the namespace, not the objects. See this interpreter example:

Python 2.3.4 (#1, Jan 9 2007, 16:40:18)
[GCC 3.4.6 20060404 (Red Hat 3.4.6-3)] on linux2
Type “help”, “copyright”, “credits” or “license” for more information.
>>> list=['foo','bar','baz']
>>> id(list)
-1209562580
>>> a=list
>>> id(a)
-1209562580
>>> list=['banf','frob','frobnitz']
>>> id(list)
-1209562324
>>> id(a)
-1209562580
>>> print a
['foo', 'bar', 'baz']

That should be very enlightening.

By: Nate Lawson

Nate Lawson — Tue, 11 Nov 2008 04:01:07 +0000

thenewsh, you may be right but these are the ones that bit me recently. It’s ok to call me lame. :)

By: newsham

newsham — Sat, 08 Nov 2008 00:31:37 +0000

I dont see what the problem with #1 is. Python is pretty clear about all variables being references to data and certain data being mutable and other data being immutable.
Similarly for #2 — these are two unrelated APIs (which can occasionally do the same thing). One joins an iterable of strings. The other joins a variable number of arguments.
The XML libraries leave much to be desired. But, hey, it’s XML :) Even when done right, it sucks.
I think there are more important python deficiencies that you can complain about :)

By: Nate Lawson

Nate Lawson — Thu, 06 Nov 2008 02:08:40 +0000

Eugene, that’s a good improvement. I’m looking forward to 3.x cleaning things up more in all areas.

By: Matt

Matt — Wed, 05 Nov 2008 19:42:31 +0000

Years ago, I read a great explanation of the Python assignment model. This was not it: http://effbot.org/zone/python-objects.htm. But, once you grok that assignment binds a name to an object and nothing more, it all comes together.

I’m really happy that they’re fixing the exception-catching syntax in 3.0.

By: Eugene Kogan

Eugene Kogan — Wed, 05 Nov 2008 18:08:10 +0000

Those are valid points, but the multiple exceptions issue is addressed in 3.0 (with 2.6 accepting both forms).

“This error happens because the use of the comma here is ambiguous: does it indicate two different nodes in the parse tree, or a single node that’s a tuple? Python 3.0 makes this unambiguous by replacing the comma with the word “as”.:

http://docs.python.org/dev/whatsnew/2.6.html#pep-3110-exception-handling-changes