Port to python3 #29
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bhipple
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Mar 22, 2020
Just requires fixing the print function, which works in python2 as well. This fixes one of the stand-alone scripts for NixOS#29.
bhipple
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Mar 22, 2020
The cmp() function was removed in python3 [1], and while there is a workaround listed, in this particular case we only need the `max` value and that's it. Aside from being simpler and py2/py3 compatible, also happens to be more performant. Partial work item for NixOS#29. Note that `2to3` *cannot* fix this particular one, hence why it's being sent in a separate PR for code review. [1] https://docs.python.org/3.0/whatsnew/3.0.html#ordering-comparisons
bhipple
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Mar 22, 2020
This runs two more fixes that are safe to merge in python2 for continued progress towards NixOS#29: 1. Converting `except T, R` to `except T as R`. Both work in python2, but only the latter works in python3. https://docs.python.org/3.0/whatsnew/3.0.html#changed-syntax 2. Converting module imports to relative imports.
bhipple
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Mar 22, 2020
In python3, `dict.items()` and `dict.values()` are iterators by defualt, so the `iteritems` functions have been removed. In python2, these return a copy of the keys, which has small runtime penalty but is unlikely to be material for NixOps. Changing it to just `.items()` makes us both py2 and py3 compatible and prepares us for the migration NixOS#29.
bhipple
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Mar 22, 2020
In py2, filter returned a list; in py3, it returns an iterator, which can't be indexed. Per upstream guidelines [1], while it is possible to just add a `list()` cast, it's more idiomatic to use a list comprehension for filtering. This is more pythonic regardless, and still py2 compatible. Partial progress towards NixOS#29 [1] https://docs.python.org/3.0/whatsnew/3.0.html#views-and-iterators-instead-of-lists
bhipple
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Mar 22, 2020
In py2, map returned a list; in py3, it returns an iterator, which can't be indexed. Per upstream guidelines [1], while it is possible to just add a list() cast, it's more idiomatic to use a list comprehension for mapping. This is more pythonic regardless, and still py2 compatible. Partial progress towards NixOS#29 CC @grahamc @AmineChikhaoui [1] https://docs.python.org/3.0/whatsnew/3.0.html#views-and-iterators-instead-of-lists
bhipple
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Mar 22, 2020
Casting to a list is a no-op in py2, but in py3 we cannot index [0] without it. Partial progress towards NixOS#29. This commit also removes unused imports from test case files as a general cleanup.
bhipple
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Mar 22, 2020
This does a 1-way migration to python3, and fully resolves NixOS#29. Aside from the `release.nix`, there are no manual changes in this PR. It was generated with: 2to3 -n -w nixopsaws/**/*.py -x dict -x print black . We have already fixed the `print` function in a previous PR, as well as all of the dictionary iterators. `2to3` is not particularly smart about this and will add a `list()` cast just about everywhere otherwise.
This was referenced Mar 22, 2020
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NixOS/nixops has moved to python3 on the
masterbranch, which means it no longer builds with thenixops-awsplugin (see NixOS/nixops#1258). A workaround is to checkout an older NixOps, but we should start the migration here as well so that the master branches work with each other.This issue tracks work items/issues/blockers/progress for python3.
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