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Tool for reordering python imports

Project description

Build Status Azure DevOps coverage

reorder_python_imports

Tool for automatically reordering python imports. Similar to isort but uses static analysis more.

Installation

pip install reorder-python-imports

Console scripts

Consult reorder-python-imports --help for the full set of options.

reorder-python-imports takes filenames as positional arguments

Common options:

  • --py##-plus: see below.
  • --add-import / --remove-import: see below.
  • --replace-import: see below.
  • --application-directories: by default, reorder-python-imports assumes your project is rooted at .. If this isn't true, tell it where your import roots live. For example, when using the popular ./src layout you'd use --application-directories=.:src (note: multiple paths are separated using a :).
  • --unclassifiable-application-module: (may be specified multiple times) modules names that are considered application modules. this setting is intended to be used for things like C modules which may not always appear on the filesystem.

As a pre-commit hook

See pre-commit for instructions

Sample .pre-commit-config.yaml

-   repo: https://github.com/asottile/reorder_python_imports
    rev: v2.1.0
    hooks:
    -   id: reorder-python-imports

What does it do?

Separates imports into three sections

import sys
import pyramid
import reorder_python_imports

becomes (stdlib, third party, first party)

import sys

import pyramid

import reorder_python_imports

import imports before from imports

from os import path
import sys

becomes

import sys
from os import path

Splits from imports

from os.path import abspath, exists

becomes

from os.path import abspath
from os.path import exists

Removes duplicate imports

import os
import os.path
import sys
import sys

becomes

import os.path
import sys

Using # noreorder

Lines containing and after lines which contain a # noreorder comment will be ignored. Additionally any imports that appear after non-whitespace non-comment lines will be ignored.

For instance, these will not be changed:

import sys

try:  # not import, not whitespace
    import foo
except ImportError:
    pass
import sys

import reorder_python_imports

import matplotlib  # noreorder
matplotlib.use('Agg')
import matplotlib.pyplot as plt
# noreorder
import sys
import pyramid
import reorder_python_imports

why this style?

The style chosen by reorder-python-imports has a single aim: reduce merge conflicts.

By having a single import per line, multiple contributors can add / remove imports from a single module without resulting in a conflict.

Consider the following example which causes a merge conflict:

# developer 1
-from typing import Dict, List
+from typing import Any, Dict, List
# developer 2
-from typing import Dict, List
+from typing import Dict, List, Tuple

no conflict with the style enforced by reorder-python-imports:

+from typing import Any
 from typing import Dict
 from typing import List
+from typing import Tuple

Adding / Removing Imports

Let's say I want to enforce absolute_import across my codebase. I can use: --add-import 'from __future__ import absolute_import'.

$ cat test.py
print('Hello world')
$ reorder-python-imports --add-import 'from __future__ import absolute_import' test.py
Reordering imports in test.py
$ cat test.py
from __future__ import absolute_import
print('Hello world')

Let's say I no longer care about supporting Python 2.5, I can remove from __future__ import with_statement with --remove-import 'from __future__ import with_statement'

$ cat test.py
from __future__ import with_statement
with open('foo.txt', 'w') as foo_f:
    foo_f.write('hello world')
$ reorder-python-imports --remove-import 'from __future__ import with_statement' test.py
Reordering imports in test.py
$ cat test.py
with open('foo.txt', 'w') as foo_f:
    foo_f.write('hello world')

Replacing imports

Imports can be replaced with others automatically (if they provide the same names). This can be useful for factoring out compatibility libraries such as six (see below for automated six rewriting).

This rewrite avoids NameErrors as such it only occurs when:

  • the imported symbol is the same before and after
  • the import is a from import

The argument is specified as orig.mod=new.mod or with an optional checked attribute orig.mod=new.mod:attr. The checked attribute is useful for renaming some imports from a module instead of a full module.

For example:

# full module move
--replace-import six.moves.queue=queue
# specific attribute move
--replace-import six.moves=io:StringIO

Removing obsolete __future__ imports

The cli provides a few options to help "burn the bridges" with old python versions by removing __future__ imports automatically. Each option implies all older versions.

  • --py22-plus: nested_scopes
  • --py23-plus: generators
  • --py26-plus: with_statement
  • --py3-plus: division, absolute_import, print_function, unicode_literals
  • --py37-plus: generator_stop

Removing / rewriting obsolete six imports

With --py3-plus, reorder-python-imports will also remove / rewrite imports from six. Rewrites follow the same rules as replacing imports above.

For example:

+import queue
+from io import StringIO
+from urllib.parse import quote_plus
+
 import six.moves.urllib.parse
-from six.moves import queue
-from six.moves import range
-from six.moves import StringIO
-from six.moves.urllib.parse import quote_plus

Project details


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