MAINT: mappingview check for Python 3.4 #8166
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lib/matplotlib/cbook/__init__.py
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| try: | ||
| from collections.abc import MappingView | ||
| except ImportError: | ||
| MappingView = None |
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Looks like the except block only applies to python 2.7, is that right?
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2.7 has mappingview (https://docs.python.org/2.7/library/collections.html#collections.MappingView) so I don't know when it can ever be triggered.
(My guess is that below, the test on whether we're running Py3 should just be removed -- we may as well sanitize the case where someone passes dic.itervalues() on Py2 too (well I always thought the whole idea was misguided but let's at least be consistent across Python versions.))
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So - collections.MappingView is present in all Python versions we support, but collections.abc.MappingView is present only for the Python 3 versions:
Changed in version 3.3: Moved Collections Abstract Base Classes to the collections.abc module. For backwards compatibility, they continue to be visible in this module as well.
https://docs.python.org/3.5/library/collections.html#module-collections
We could use collections.MappingView directly, they haven't been deprecated, I guess.
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I vote for using collections.MappingView directly then as I think the if MappingView = None is clunky
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Right but I also felt it expressed the intention more clearly.
…On 28 Feb 2017 16:19, "Paul Hobson" ***@***.***> wrote:
***@***.**** approved this pull request.
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In lib/matplotlib/cbook/__init__.py
<#8166 (comment)>
:
> @@ -13,6 +13,12 @@
from six.moves import xrange, zip
from itertools import repeat
import collections
+
+try:
+ from collections.abc import MappingView
+except ImportError:
+ MappingView = None
Looks like the except block only applies to python 2.7, is that right?
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@matthew-brett totally. I just wanted to make sure I understood it properly since I don't have a py2.7 installation handy. |
lib/matplotlib/cbook/__init__.py
Outdated
| try: | ||
| from collections.abc import MappingView | ||
| except ImportError: | ||
| MappingView = None |
There was a problem hiding this comment.
2.7 has mappingview (https://docs.python.org/2.7/library/collections.html#collections.MappingView) so I don't know when it can ever be triggered.
(My guess is that below, the test on whether we're running Py3 should just be removed -- we may as well sanitize the case where someone passes dic.itervalues() on Py2 too (well I always thought the whole idea was misguided but let's at least be consistent across Python versions.))
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Side question: Codecov says this line is covered, so how was that never caught before in the CI? (Unfortunately Travis doesn't want to load for me right now.) |
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I'm just guessing, but I suspect that some versions of Python 3.4 do an automatic import of That's just a guess, because the behavior above is so for all the Python3.4s I could find. |
Python 3.4 does not automatically import module `abc` into `collections`, causing an error when checking for `collections.abc.MappingView`. Use `collections.MappingView` to work round this difference. At some point Python may deprecate `collections.MappingView` in favor of `collections.abc.MappingView` but we can fix that when it arises.
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LGTM (conditional on tests passing). |
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It looks like |
Python 3.4 does not autoamatically import module
abcintocollections, causing an error when checking forcollections.abc.MappingView. Do more explicit import ofMappingViewto work round this difference.
See: https://travis-ci.org/MacPython/matplotlib-wheels/jobs/205713297#L582 for
error on Python 3.4.