Don't unnecessarily copy the key list

[dmitchell]

__iter__, has_key, __contains__, clear, & len all copy the __keys list but don't need to.

Minor backward compatibility change: make __iter__ generate a runtime error if the user attempts to destructively modify the SON during iteration just as dict does and have the others directly use the internal list.

[dmitchell]

Issue https://jira.mongodb.org/browse/PYTHON-703

[dmitchell]

We also need this as tag 2.4.1a based on tag 2.4.1. We can maintain that in our fork for now if that's preferable.

[behackett]

This doesn't appear to be enforced by collections.OrderedDict, so I don't think we want to enforce it here.

http://hg.python.org/releasing/3.4.1/file/ea310ca42bb2/Lib/collections/__init__.py#l83

[dmitchell]

Cool. Thanks for noticing. I'll change it.

[dmitchell]

I assume it should act the same was as it would if iterating over a list then: that is, any destructive operations can cause unexpected behavior such as this shows (iteration skips an ele due to the removal of a prior ele):

>>> a = [1, 2, 3]
>>> for ele in a:
...     print ele
...     a.remove(ele)
... 
1
3
>>> a
[2]
>>> 

[behackett]

>>> od = OrderedDict([('a', 1), ('b', 2), ('c', 3)])
>>> for key in od:
...     print key
...     del od[key]
... 
a
b
c
>>> od
OrderedDict()
>>> for key in od:
...     print key
... 
>>> 

>>> from bson.son import SON
>>> s = SON([('a', 1), ('b', 2), ('c', 3)])
>>> for key in s:
...     print key
...     del s[key]
... 
a
b
c
>>> s
SON([])
>>> for key in s:
...     print key
... 

[behackett]

Thanks for the patch. Most of the changes seem reasonable to me. We won't release a 2.4.x version of the driver for this though. That's pretty old and a ton of bugs have been fixed since 2.4.

[dmitchell]

Alas, this didn't improve performance enough; so, we're back to using dict
and worrying about instable subdoc order.

On Wed, Jun 4, 2014 at 4:21 PM, Bernie Hackett notifications@github.com
wrote:

Thanks for the patch. Most of the changes seem reasonable to me. We won't
release a 2.4.x version of the driver for this though. That's pretty old
and a ton of bugs have been fixed since 2.4.

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#238 (comment)
.

[behackett]

You can use collections.OrderedDict with PyMongo. bson.son.SON really only exists because PyMongo supports python versions older than python 2.7. Using some trivial benchmarks we've found that SON serializes a bit faster than OrderedDict. Your mileage may vary.

[dmitchell]

We found the same dict << SON < OrderedDict

On Fri, Jun 6, 2014 at 10:51 AM, Bernie Hackett notifications@github.com
wrote:

You can use collections.OrderedDict with PyMongo. bson.son.SON really only
exists because PyMongo supports python versions older than python 2.7.
Using some trivial benchmarks we've found that SON serializes a bit faster
than OrderedDict. Your mileage may vary.

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#238 (comment)
.

[ajdavis]

Merged into 2.8 and 3.0 release branches. Thanks for the contribution!