Flake8 plugin that checks import order against various Python Style Guides
|Build Status|
A
flake8__ and
Pylama__ plugin that checks the ordering of your imports. It does not check anything else about the imports. Merely that they are grouped and ordered correctly.
In general stdlib comes first, then 3rd party, then local packages, and that each group is individually alphabetized, however this depends on the style used. Flake8-Import-Order supports a number of
styles_ and is extensible allowing for
custom styles_.
This plugin was originally developed to match the style preferences of the
cryptography__ project, with this style remaining the default.
This package adds 4 new flake8 warnings
I100: Your import statements are in the wrong order.
I101: The names in your from import are in the wrong order.
I201: Missing newline between import groups.
I202: Additional newline in a group of imports.
The following styles are directly supported,
cryptography- see an
example__
Google Style Guidelines, see an
example
smarkets- style as
importstatements before
from X import ...statements, see an
example__
appnexus- style as
importstatements for packages local to your company or organisation coming after
importstatements for third-party packages, see an
example__
edited- see an
example__
pycharm- style as
smarketsonly with case sensitive sorting imported names
pep8- style that only enforces groups without enforcing the order within the groups
You can also
add your own style_ by extending
Styleclass.
You will want to set the
application-import-namesoption to a comma separated list of names that should be considered local to your application. These will be used to help categorise your import statements into the correct groups. Note that relative imports are always considered local.
You will want to set the
application-package-namesoption to a comma separated list of names that should be considered local to your company or organisation, but which are obtained using some sort of package manager like Pip, Apt, or Yum. Typically, code representing the values listed in this option is located in a different repository than the code being developed. This option is only accepted in the supported
appnexusor
editedstyles or in any style that accepts application package names.
The
application-import-namesand
application-package-namescan contain namespaced packages or even exact nested module names. (This is possible with 0.16 onwards).
import-order-stylecontrols what style the plugin follows (
cryptographyis the default).
Currently these checks are limited to module scope imports only. Conditional imports in module scope will also be ignored.
Classification of an imported module is achieved by checking the module against a stdlib list and then if there is no match against the
application-import-nameslist and
application-package-namesif the style accepts application-package names. Only if none of these lists contain the imported module will it be classified as third party.
These checks only consider an import against its previous import, rather than considering all the imports together. This means that
I100errors are only raised for the latter of adjacent imports out of order. For example,
.. code-block:: python
import X.B import X # I100 import X.A
only
import Xraises an
I100error, yet
import X.Ais also out of order compared with the
import X.B.
Imported modules are classified as stdlib if the module is in a vendored list of stdlib modules. This list is based on the latest release of Python and hence the results can be misleading. This list is also the same for all Python versions because otherwise it would be impossible to write programs that work under both Python 2 and 3 and pass the import order check.
The
I202check will consider any blank line between imports to count, even if the line is not contextually related to the imports. For example,
.. code-block:: python
import logging try: from logging import NullHandler except ImportError: class NullHandler(logging.Handler): """Shim for version of Python < 2.7."""def emit(self, record): pass
import sys # I202 due to the blank line before the 'def emit'
will trigger a
I202error despite the blank line not being contextually related.
You can add your own style by extending
flake8_import_order.styles.Styleclass. Here's an example:
.. code-block:: python
from flake8_import_order.styles import Cryptographyclass ReversedCryptography(Cryptography): # Note that Cryptography is a subclass of Style.
@staticmethod def sorted_names(names): return reversed(Cryptography.sorted_names(names))
By default there are five import groupings or sections; future, stdlib, third party, application, and relative imports. A style can choose to accept another grouping, application-package, by setting the
Styleclass variable
accepts_application_package_namesto True, e.g.
.. code-block:: python
class PackageNameCryptography(Cryptography): accepts_application_package_names = True
To make flake8-import-order able to discover your extended style, you need to register it as
flake8_import_order.stylesusing setuptools'
entry points__ mechanism:
.. code-block:: python
# setup.py of your style package setup( name='flake8-import-order-reversed-cryptography', ..., entry_points={ 'flake8_import_order.styles': [ 'reversed = reversedcryptography:ReversedCryptography', # 'reversed' is a style name. You can pass it to # --import-order-style option # 'reversedcryptography:ReversedCryptography' is an import path # of your extended style class. ] } )
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