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Description:

removestar 1.5.1

removestar

Tool to automatically replace import * imports in Python files with explicit imports
Installation
Install removestar globally to use it through CLI using pypi -
pip install removestar
pip install "removestar[nb]" # notebook support

or conda -
conda install -c conda-forge removestar

or add removestar in .pre-commit-config.yaml -
- repo: https://github.com/asmeurer/removestar
rev: "1.5"
hooks:
- id: removestar
args: [-i] # See docs for all args (-i edits file in-place)
additional_dependencies: # The libraries or packages your code imports
- ... # Add . if running inside a library (to install the library itself in the environment)
- ... # Add nbformat and nbconvert for notebook support

Usage
pre-commit hook
Once removestar is added in .pre-commit-config.yaml, executing the following
will always run it (and other pre-commits) before every commit -
pre-commit install

Optionally, the pre-commits (including removestar) can be manually triggered for
all the files using -
pre-commit run --all-files

CLI
# scripts

$ removestar file.py # Shows diff but does not edit file.py

$ removestar -i file.py # Edits file.py in-place

$ removestar -i module/ # Modifies every Python file in module/ recursively

# notebooks (make sure nbformat and nbconvert are installed)

$ removestar file.ipynb # Shows diff but does not edit file.ipynb

$ removestar -i file.ipynb # Edits file.ipynb in-place

Why is import * so bad?
Doing from module import * is generally frowned upon in Python. It is
considered acceptable when working interactively at a python prompt, or in
__init__.py files (removestar skips __init__.py files by default).
Some reasons why import * is bad:

It hides which names are actually imported.
It is difficult both for human readers and static analyzers such as
pyflakes to tell where a given name comes from when import * is used. For
example, pyflakes cannot detect unused names (for instance, from typos) in
the presence of import *.
If there are multiple import * statements, it may not be clear which names
come from which module. In some cases, both modules may have a given name,
but only the second import will end up being used. This can break people's
intuition that the order of imports in a Python file generally does not
matter.
import * often imports more names than you would expect. Unless the module
you import defines __all__ or carefully dels unused names at the module
level, import * will import every public (doesn't start with an
underscore) name defined in the module file. This can often include things
like standard library imports or loop variables defined at the top-level of
the file. For imports from modules (from __init__.py), from module import * will include every submodule defined in that module. Using __all__ in
modules and __init__.py files is also good practice, as these things are
also often confusing even for interactive use where import * is
acceptable.
In Python 3, import * is syntactically not allowed inside of a function.

Here are some official Python references stating not to use import * in
files:

The official Python
FAQ:

In general, don’t use from modulename import *. Doing so clutters the
importer’s namespace, and makes it much harder for linters to detect
undefined names.

PEP 8 (the official
Python style guide):

Wildcard imports (from <module> import *) should be avoided, as they
make it unclear which names are present in the namespace, confusing both
readers and many automated tools.

Unfortunately, if you come across a file in the wild that uses import *, it
can be hard to fix it, because you need to find every name in the file that is
imported from the *. Removestar makes this easy by finding which names come
from * imports and replacing the import lines in the file automatically.
One exception where import * can be bneficial:
At the early stages of code development, a definite set of required
functions can be difficult to determine. In such a context, wildcard imports could be
beneficial by avoiding constantly curating the set of required functions. For example,
at the development stage usage of from os.path import * can save time from curating
required functions. Post-development, the wld card imports could be determined using
removestar. Having said that, because of the multiple said reasons, wildcard imports
should be avoided.
Example
Suppose you have a module mymod like
mymod/
| __init__.py
| a.py
| b.py

With
# mymod/a.py
from .b import *

def func(x):
return x + y

# mymod/b.py
x = 1
y = 2

Then removestar works like:
$ removestar mymod/

--- original/mymod/a.py
+++ fixed/mymod/a.py
@@ -1,5 +1,5 @@
# mymod/a.py
-from .b import *
+from .b import y

def func(x):
return x + y

This does not edit a.py by default. The -i flag causes it to edit a.py in-place:
$ removestar -i mymod/
$ cat mymod/a.py
# mymod/a.py
from .b import y

def func(x):
return x + y

Command line options

$ removestar --help
usage: removestar [-h] [-i] [--version] [--no-skip-init]
[--no-dynamic-importing] [-v] [-q]
[--max-line-length MAX_LINE_LENGTH]
PATH [PATH ...]

Tool to automatically replace "import *" imports with explicit imports

Requires pyflakes.

Usage:

$ removestar file.py # Shows diff but does not edit file.py

$ removestar -i file.py # Edits file.py in-place

$ removestar -i module/ # Modifies every Python file in module/ recursively

positional arguments:
PATH Files or directories to fix

optional arguments:
-h, --help show this help message and exit
-i, --in-place Edit the files in-place. (default: False)
--version Show removestar version number and exit.
--no-skip-init Don't skip __init__.py files (they are skipped by
default) (default: True)
--no-dynamic-importing
Don't dynamically import modules to determine the list
of names. This is required for star imports from
external modules and modules in the standard library.
(default: True)
-v, --verbose Print information about every imported name that is
replaced. (default: False)
-q, --quiet Don't print any warning messages. (default: False)
--max-line-length MAX_LINE_LENGTH
The maximum line length for replaced imports before
they are wrapped. Set to 0 to disable line wrapping.
(default: 100)

Whitelisting star imports
removestar does not replace star import lines that are marked with
Flake8 noqa comments that permit star imports (F401 or
F403).
For example, the star imports in this module would be kept:
from os import * # noqa: F401
from .b import * # noqa

def func(x):
return x + y

Current limitations

Assumes only names in the current file are used by star imports (e.g., it
won't work to replace star imports in __init__.py).

For files within the same module, removestar determines missing imported names
statically. For external library imports, including imports of standard
library modules, it dynamically imports the module to determine the names.
This can be disabled with the --no-dynamic-importing flag.

Contributing
See the issue tracker. Pull
requests are welcome.
Changelog
See the CHANGELOG file.
License
MIT