PyCQA/ flake8-import-order

Python

flake8

linter-plugin

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PyCQA

247 Stars

60 Forks

GNU Lesser General Public License v3.0

274 Commits

13 Opened issues

Description

Flake8 plugin that checks import order against various Python Style Guides

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flake8-import-order

Name: flake8-import-order
Brand: flake8-import-order
SKU: //PyCQA/flake8-import-order
Rating: 2.3675 (247 reviews)

|Build Status|

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.

Warnings

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.

Styles

The following styles are directly supported,

```
cryptography
```
- see an
```
example 
```
__
```
google
```
- style described in
```
Google Style Guidelines 
```
, see an
example
```
smarkets
```
- style as
```
google
```
only with
```
import
```
statements before
```
from X import ...
```
statements, see an
```
example 
```
__
```
appnexus
```
- style as
```
google
```
only with
```
import
```
statements for packages local to your company or organisation coming after
```
import
```
statements for third-party packages, see an
```
example 
```
__
```
edited
```
- see an
```
example 
```
__
```
pycharm
```
- style as
```
smarkets
```
only 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

Style

class.

Configuration

You will want to set the

application-import-names

option 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-names

option 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

appnexus

edited

styles or in any style that accepts application package names.

The

application-import-names

and

application-package-names

can contain namespaced packages or even exact nested module names. (This is possible with 0.16 onwards).

import-order-style

controls what style the plugin follows (

cryptography

is the default).

Limitations

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-names

list and

application-package-names

if 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

I100

errors 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 X

raises an

I100

error, yet

import X.A

is 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

I202

check 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

I202

error despite the blank line not being contextually related.

Extending styles

You can add your own style by extending

flake8_import_order.styles.Style

class. Here's an example:

.. code-block:: python

from flake8_import_order.styles import Cryptography


class 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

Style

class variable

accepts_application_package_names

to 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.styles

using 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.
        ]
    }
)

.. |Build Status| image:: https://travis-ci.org/PyCQA/flake8-import-order.svg?branch=master :target: https://travis-ci.org/PyCQA/flake8-import-order