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For example:\n\n  \u003e\u003e\u003e x \u003d [\u0027foo\u0027, \u0027bar\u0027, None, \u0027qux\u0027]\n  \u003e\u003e\u003e sorted(x)\n  Traceback (most recent call last):\n    File \"\u003cstdin\u003e\", line 1, in \u003cmodule\u003e\n  TypeError: \u0027\u003c\u0027 not supported between instances of \u0027NoneType\u0027 and \u0027str\u0027\n\nFortunately, we can take advantage of the fact that by providing a\nfunction for the \u0027key\u0027 that returns a tuple, we can sort on multiple\nconditions. In this case, \"when the first key returns that two elements\nare equal, the second key is used to compare.\" [1] We can use this to\nfirst separate the values by whether they are None or not, punting those\nthat are not to the end, before sorting the non-None values normally.\nFor example:\n\n  \u003e\u003e\u003e x \u003d [\u0027foo\u0027, \u0027bar\u0027, None, \u0027qux\u0027]\n  \u003e\u003e\u003e sorted(x, key\u003dlambda k: (k is None, k))\n  [\u0027bar\u0027, \u0027foo\u0027, \u0027qux\u0027, None]\n\nWe were already using this feature implicitly through our use of\n\u0027operator.itemgetter(*indexes)\u0027, which will return a tuple if there is\nmore than one item in \u0027indexes\u0027, and now we simply make that explicit,\nfixing the case where we\u0027re attempting to compare a comparable type\nwith None. For all other cases, such as comparing a value that isn\u0027t\ncomparable, we surround things with a try-catch and a debug logging\nstatement to allow things to continue.\n\nNote that we could optimize what we\u0027re done further by building a key\nvalue that covers all indexes, rather than using a for loop to do so.\nFor example:\n\n  \u003e\u003e\u003e x \u003d [(\u0027baz\u0027, 2), (None, 0), (\u0027bar\u0027, 3), (\u0027baz\u0027, 4), (\u0027qux\u0027, 0)]\n  \u003e\u003e\u003e sorted(x, key\u003dlambda k: list(\n  ...     itertools.chain((k[i] is None, k[i]) for i in (0, 1)))\n  ... )\n  [(\u0027bar\u0027, 3), (\u0027baz\u0027, 2), (\u0027baz\u0027, 4), (\u0027qux\u0027, 0), (None, 0)]\n\nHowever, this would be harder to grok and would also mean we\u0027re unable\nto handle exceptions on a single column where e.g. there are mixed types\nor types that are not comparable while still sorting on the other\ncolumns. Perhaps this would be desirable for some users, but sorting on\na best-effort basis does seem wiser and generally more user friendly.\nAnyone that wants to sort on such columns should ensure their types are\ncomparable or implement their own sorting implementation.\n\n[1] https://www.kite.com/python/answers/how-to-sort-by-two-keys-in-python\n\nChange-Id: I4803051a6dd05c143a15923254af97e32cd39693\nSigned-off-by: Stephen Finucane \u003csfinucan@redhat.com\u003e\nStory: 2008456\nTask: 41466\n","web_links":[{"name":"gitea","tooltip":"Open in GitWeb","url":"https://opendev.org/openstack/cliff/commit/609b2fc987664b77a51ab9f099461440a04202f9"}],"resolve_conflicts_web_links":[{"name":"gitea","tooltip":"Open in GitWeb","url":"https://opendev.org/openstack/cliff/commit/609b2fc987664b77a51ab9f099461440a04202f9"}]},"branch":"refs/heads/master"},"e86f653b91c210ddcc9136d8fba61ae1c44b8e92":{"kind":"REWORK","_number":2,"created":"2021-01-28 16:14:06.000000000","uploader":{"_account_id":15334,"name":"Stephen Finucane","display_name":"stephenfin","email":"stephenfin@redhat.com","username":"sfinucan"},"ref":"refs/changes/54/772854/2","fetch":{"anonymous http":{"url":"https://review.opendev.org/openstack/cliff","ref":"refs/changes/54/772854/2","commands":{"Checkout":"git fetch https://review.opendev.org/openstack/cliff refs/changes/54/772854/2 \u0026\u0026 git checkout FETCH_HEAD","Cherry Pick":"git fetch https://review.opendev.org/openstack/cliff refs/changes/54/772854/2 \u0026\u0026 git cherry-pick FETCH_HEAD","Format Patch":"git fetch https://review.opendev.org/openstack/cliff refs/changes/54/772854/2 \u0026\u0026 git format-patch -1 --stdout FETCH_HEAD","Pull":"git pull https://review.opendev.org/openstack/cliff refs/changes/54/772854/2"}}},"commit":{"parents":[{"commit":"36134739396213fa11d1c4ca1e9cacb8f40215eb","subject":"gitignore: Ignore reno artefacts","web_links":[{"name":"gitea","tooltip":"Open in GitWeb","url":"https://opendev.org/openstack/cliff/commit/36134739396213fa11d1c4ca1e9cacb8f40215eb"}]}],"author":{"name":"Stephen Finucane","email":"sfinucan@redhat.com","date":"2021-01-27 17:31:22.000000000","tz":0},"committer":{"name":"Stephen Finucane","email":"sfinucan@redhat.com","date":"2021-01-28 16:13:47.000000000","tz":0},"subject":"Handle null values when sorting","message":"Handle null values when sorting\n\nOne unfortunate change (or fortunate, depending on how you look at\ntypes) in Python 3 is the inability to sort iterables of different\ntypes. For example:\n\n  \u003e\u003e\u003e x \u003d [\u0027foo\u0027, \u0027bar\u0027, None, \u0027qux\u0027]\n  \u003e\u003e\u003e sorted(x)\n  Traceback (most recent call last):\n    File \"\u003cstdin\u003e\", line 1, in \u003cmodule\u003e\n  TypeError: \u0027\u003c\u0027 not supported between instances of \u0027NoneType\u0027 and \u0027str\u0027\n\nFortunately, we can take advantage of the fact that by providing a\nfunction for the \u0027key\u0027 that returns a tuple, we can sort on multiple\nconditions. In this case, \"when the first key returns that two elements\nare equal, the second key is used to compare.\" [1] We can use this to\nfirst separate the values by whether they are None or not, punting those\nthat are not to the end, before sorting the non-None values normally.\nFor example:\n\n  \u003e\u003e\u003e x \u003d [\u0027foo\u0027, \u0027bar\u0027, None, \u0027qux\u0027]\n  \u003e\u003e\u003e sorted(x, key\u003dlambda k: (k is None, k))\n  [\u0027bar\u0027, \u0027foo\u0027, \u0027qux\u0027, None]\n\nWe were already using this feature implicitly through our use of\n\u0027operator.itemgetter(*indexes)\u0027, which will return a tuple if there is\nmore than one item in \u0027indexes\u0027, and now we simply make that explicit,\nfixing the case where we\u0027re attempting to compare a comparable type\nwith None. For all other cases, such as comparing a value that isn\u0027t\ncomparable, we surround things with a try-catch and a debug logging\nstatement to allow things to continue.\n\nNote that we could optimize what we\u0027re done further by building a key\nvalue that covers all indexes, rather than using a for loop to do so.\nFor example:\n\n  \u003e\u003e\u003e x \u003d [(\u0027baz\u0027, 2), (None, 0), (\u0027bar\u0027, 3), (\u0027baz\u0027, 4), (\u0027qux\u0027, 0)]\n  \u003e\u003e\u003e sorted(x, key\u003dlambda k: list(\n  ...     itertools.chain((k[i] is None, k[i]) for i in (0, 1)))\n  ... )\n  [(\u0027bar\u0027, 3), (\u0027baz\u0027, 2), (\u0027baz\u0027, 4), (\u0027qux\u0027, 0), (None, 0)]\n\nHowever, this would be harder to grok and would also mean we\u0027re unable\nto handle exceptions on a single column where e.g. there are mixed types\nor types that are not comparable while still sorting on the other\ncolumns. Perhaps this would be desirable for some users, but sorting on\na best-effort basis does seem wiser and generally more user friendly.\nAnyone that wants to sort on such columns should ensure their types are\ncomparable or implement their own sorting implementation.\n\n[1] https://www.kite.com/python/answers/how-to-sort-by-two-keys-in-python\n\nChange-Id: I4803051a6dd05c143a15923254af97e32cd39693\nSigned-off-by: Stephen Finucane \u003csfinucan@redhat.com\u003e\nStory: 2008456\nTask: 41466\n","web_links":[{"name":"gitea","tooltip":"Open in GitWeb","url":"https://opendev.org/openstack/cliff/commit/e86f653b91c210ddcc9136d8fba61ae1c44b8e92"}],"resolve_conflicts_web_links":[{"name":"gitea","tooltip":"Open in GitWeb","url":"https://opendev.org/openstack/cliff/commit/e86f653b91c210ddcc9136d8fba61ae1c44b8e92"}]},"branch":"refs/heads/master"},"4f45f9a30e657265c5b5ac119af3aaa0e5ec7184":{"kind":"REWORK","_number":3,"created":"2021-01-29 15:40:54.000000000","uploader":{"_account_id":15334,"name":"Stephen Finucane","display_name":"stephenfin","email":"stephenfin@redhat.com","username":"sfinucan"},"ref":"refs/changes/54/772854/3","fetch":{"anonymous http":{"url":"https://review.opendev.org/openstack/cliff","ref":"refs/changes/54/772854/3","commands":{"Checkout":"git fetch https://review.opendev.org/openstack/cliff refs/changes/54/772854/3 \u0026\u0026 git checkout FETCH_HEAD","Cherry Pick":"git fetch https://review.opendev.org/openstack/cliff refs/changes/54/772854/3 \u0026\u0026 git cherry-pick FETCH_HEAD","Format Patch":"git fetch https://review.opendev.org/openstack/cliff refs/changes/54/772854/3 \u0026\u0026 git format-patch -1 --stdout FETCH_HEAD","Pull":"git pull https://review.opendev.org/openstack/cliff refs/changes/54/772854/3"}}},"commit":{"parents":[{"commit":"36134739396213fa11d1c4ca1e9cacb8f40215eb","subject":"gitignore: Ignore reno artefacts","web_links":[{"name":"gitea","tooltip":"Open in GitWeb","url":"https://opendev.org/openstack/cliff/commit/36134739396213fa11d1c4ca1e9cacb8f40215eb"}]}],"author":{"name":"Stephen Finucane","email":"sfinucan@redhat.com","date":"2021-01-27 17:31:22.000000000","tz":0},"committer":{"name":"Stephen Finucane","email":"sfinucan@redhat.com","date":"2021-01-29 15:40:31.000000000","tz":0},"subject":"Handle null values when sorting","message":"Handle null values when sorting\n\nOne unfortunate change (or fortunate, depending on how you look at\ntypes) in Python 3 is the inability to sort iterables of different\ntypes. For example:\n\n  \u003e\u003e\u003e x \u003d [\u0027foo\u0027, \u0027bar\u0027, None, \u0027qux\u0027]\n  \u003e\u003e\u003e sorted(x)\n  Traceback (most recent call last):\n    File \"\u003cstdin\u003e\", line 1, in \u003cmodule\u003e\n  TypeError: \u0027\u003c\u0027 not supported between instances of \u0027NoneType\u0027 and \u0027str\u0027\n\nFortunately, we can take advantage of the fact that by providing a\nfunction for the \u0027key\u0027 that returns a tuple, we can sort on multiple\nconditions. In this case, \"when the first key returns that two elements\nare equal, the second key is used to compare.\" [1] We can use this to\nfirst separate the values by whether they are None or not, punting those\nthat are not to the end, before sorting the non-None values normally.\nFor example:\n\n  \u003e\u003e\u003e x \u003d [\u0027foo\u0027, \u0027bar\u0027, None, \u0027qux\u0027]\n  \u003e\u003e\u003e sorted(x, key\u003dlambda k: (k is None, k))\n  [\u0027bar\u0027, \u0027foo\u0027, \u0027qux\u0027, None]\n\nWe were already using this feature implicitly through our use of\n\u0027operator.itemgetter(*indexes)\u0027, which will return a tuple if there is\nmore than one item in \u0027indexes\u0027, and now we simply make that explicit,\nfixing the case where we\u0027re attempting to compare a comparable type\nwith None. For all other cases, such as comparing a value that isn\u0027t\ncomparable, we surround things with a try-catch and a debug logging\nstatement to allow things to continue.\n\nNote that we could optimize what we\u0027re done further by building a key\nvalue that covers all indexes, rather than using a for loop to do so.\nFor example:\n\n  \u003e\u003e\u003e x \u003d [(\u0027baz\u0027, 2), (None, 0), (\u0027bar\u0027, 3), (\u0027baz\u0027, 4), (\u0027qux\u0027, 0)]\n  \u003e\u003e\u003e sorted(x, key\u003dlambda k: list(\n  ...     itertools.chain((k[i] is None, k[i]) for i in (0, 1)))\n  ... )\n  [(\u0027bar\u0027, 3), (\u0027baz\u0027, 2), (\u0027baz\u0027, 4), (\u0027qux\u0027, 0), (None, 0)]\n\nHowever, this would be harder to grok and would also mean we\u0027re unable\nto handle exceptions on a single column where e.g. there are mixed types\nor types that are not comparable while still sorting on the other\ncolumns. Perhaps this would be desirable for some users, but sorting on\na best-effort basis does seem wiser and generally more user friendly.\nAnyone that wants to sort on such columns should ensure their types are\ncomparable or implement their own sorting implementation.\n\n[1] https://www.kite.com/python/answers/how-to-sort-by-two-keys-in-python\n\nChange-Id: I4803051a6dd05c143a15923254af97e32cd39693\nSigned-off-by: Stephen Finucane \u003csfinucan@redhat.com\u003e\nStory: 2008456\nTask: 41466\n","web_links":[{"name":"gitea","tooltip":"Open in GitWeb","url":"https://opendev.org/openstack/cliff/commit/4f45f9a30e657265c5b5ac119af3aaa0e5ec7184"}],"resolve_conflicts_web_links":[{"name":"gitea","tooltip":"Open in GitWeb","url":"https://opendev.org/openstack/cliff/commit/4f45f9a30e657265c5b5ac119af3aaa0e5ec7184"}]},"branch":"refs/heads/master"}},"requirements":[],"submit_records":[{"status":"CLOSED","labels":[{"label":"Verified","status":"OK","applied_by":{"_account_id":22348,"name":"Zuul","username":"zuul","tags":["SERVICE_USER"]}},{"label":"Code-Review","status":"OK","applied_by":{"_account_id":27900,"name":"Artem Goncharov","email":"artem.goncharov@gmail.com","username":"gtema"}},{"label":"Workflow","status":"OK","applied_by":{"_account_id":27900,"name":"Artem Goncharov","email":"artem.goncharov@gmail.com","username":"gtema"}}]}],"submit_requirements":[{"name":"Verified","status":"SATISFIED","is_legacy":true,"submittability_expression_result":{"expression":"label:Verified\u003dCustom-Rule","fulfilled":true,"status":"PASS","passing_atoms":["label:Verified\u003dCustom-Rule"],"failing_atoms":[],"atom_explanations":{}}},{"name":"Workflow","status":"SATISFIED","is_legacy":true,"submittability_expression_result":{"expression":"label:Workflow\u003dCustom-Rule","fulfilled":true,"status":"PASS","passing_atoms":["label:Workflow\u003dCustom-Rule"],"failing_atoms":[],"atom_explanations":{}}},{"name":"Code-Review","status":"SATISFIED","is_legacy":true,"submittability_expression_result":{"expression":"label:Code-Review\u003dCustom-Rule","fulfilled":true,"status":"PASS","passing_atoms":["label:Code-Review\u003dCustom-Rule"],"failing_atoms":[],"atom_explanations":{}}}]}