[Pulp-list] Interesting python inspection

[Bryan Kearney]

On 08/19/2010 12:55 PM, Jason Dobies wrote:
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> On 08/19/2010 12:55 PM, Jason Rist wrote:
>> On 08/19/2010 10:28 AM, Jason Dobies wrote:
>>> PyCharm just flagged the following code with a warning (in particular
>>> the consumerids argument)
>>>
>>> def create(self, id, description, consumerids=[]):
>>>
>>> Here's the warning:
>>>
>>> "This inspection detects when a mutable value as list or dictionary is
>>> detected in a default value for an argument. Default argument values are
>>> evaluated only once at function definition time, which means that
>>> modifying the default value of the argument will affect all subsequent
>>> calls of the function. "
>>>
>>> That's kinda cool, I never saw anything like that before.
>>>
>> It knows...
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>
> Something else I keep seeing in the code is:
>
> if foo == None:
>
> It's better to just use object reference comparison rather than equality
> when checking for none:
>
> if foo is None:
>
>

Why?

-- bk