Checking against NULL will be eliminated?

[Philip Semanchuk]

On Mar 2, 2011, at 9:21 AM, Stefan Behnel wrote:

> Claudiu Popa, 02.03.2011 14:51:
>> Hello Python-list,
>> 
>> 
>> I  don't  know how to call it, but the following Python 3.2 code seems to raise a
>> FutureWarning.
>> 
>> def func(root=None):
>>     nonlocal arg
>>     if root:
>>        arg += 1
>> The  warning is "FutureWarning: The behavior of this method will change
>> in future versions.  Use specific 'len(elem)' or 'elem is not None' test instead."
>> Why is the reason for this idiom to be changed?
> 
> Let me guess - this is using ElementTree, right?
> 
> It's not the idiom itself that changes, it's the Element class in ElementTree that will likely change its behaviour in later versions.
> 
> Fix: do as it says.

And it's documented, although you might have a hard time finding it. See the "Caution" at the end of this section of documentation:
http://docs.python.org/py3k/library/xml.etree.elementtree.html#element-objects

I wish this behavior had been changed for Python 3.x. That warning has been in the ElementTree doc since before it became part of the standard lib, so it's not a new idea. Python 3.x seems like it would have been an ideal time to make the change. Oh well.

bye
P