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Smoother Python with automatic imports | pyflyby

waylonwalker

Waylon Walker

Posted on December 21, 2021

Smoother Python with automatic imports | pyflyby

This is not a flaky works half the time kind of plugin, its a seriously smooth editing experience. I've just started using pyflyby and it is solid so far. I have automatic imports on every save of a python file in neovim, and automatic imports on every command in ipython.

I can't tell you how pumped I am for this, and how good its felt to use over the past few weeks. It's glorious.

YouTube video

Listen to me rant on how great pyflyby is

Give the video a watch, I did not have noise cancelling on in obs. My appologies for the background hum and the mic stand bumps. I did my best to fix them up.

installation

How to install pyflyby for automatic python imports

pyflypy is hosted on pypi, so you can get it with pip. I have had no issues installing it on 3.8+ so far.

pip install flybypy
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configuration setup with stow

always stow your dotfiles

If you're going to configure any of your tools the first thing you should do is set it up with stow, seriously dont sleep on the stow. If you don't have stow installed or choose not to use stow you can skip this part.

cd ~/dotfiles
mkdir ipython
touch ipython/.pyflyby
stow ipython
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Seriously don't sleep on the stow.

How to Configure pyflyby

its just a file full of import statements

pyflyby is configured simply by putting all of your import statements that you want to automatically import into your ~/.pyflyby file. You can import pandas, from pandas import DataFrame, or even import pandas as pd, and all of these will work pretty much as expected.

# comments start with a #
# import your favorite libraries
import visidata as vd
import fsspec
import difflib
import s3fs
import seaborn as sns
import plotly

# also supports from imports
from rich.layout import Layout
from rich.live import Live

# duplicates are allowed
import plotly
import plotly

# duplicate names from different libraries are not allowed
import copy
from numpy import copy
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Add all the things you would like to be imported automatically, just as you would import them. I went kinda crazy and added over 200 to mine based on packages that I use.

Commas are even supported

yep all the import styles are supported

This following example will setup auto import for both DataFrame and Series, they will both work separately. I removed these from my config as I felt it was cleaner without, but it works with them.

from pandas import DataFrame, Series
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Even imports with a comma will be treated separately.

jupyter note!

Both work the same, use what your comfortable with

I only really mention ipython here, but the same all applies to jupyter as well. I just really like ipython itself, c'mon its right there in the terminal integrating with the rest of your terminal experience so well.

ipython setup

Automatically import python libraries in ipython with pyflyby

The recommended way to setup flybypy from the docs is to run the following magic command. This works well, but I wan even less typing, I want pyflyby automatically installed and importing things without me even thinking about it.

%load_ext pyflyby
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ipython setup next level

automatically import modules in python without %load_ext

I really want pyflyby to just work in every environment without me thinking much about it. I want it to load automatically, and even to attempt to install itself if its missing.

from IPython import get_ipython
import subprocess


ipython = get_ipython()

try:
    ipython.magic("load_ext pyflyby")
except ModuleNotFoundError:
    print("installing pyflyby")
    subprocess.Popen(
        ["pip", "install", "pyflyby"],
        stdout=subprocess.DEVNULL,
        stderr=subprocess.DEVNULL,
    ).wait()
    ipython.magic("load_ext pyflyby")
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Note: if installation fails you will still make it into ipython, there will just be a traceback to the failed command as you enter.

I've had zero issues with this, but if there ever comes a time where it does not work in certain environments for you. I'd strongly suggest you to add this to a separate profile.


article cover for Ipython-Config

Check out this article for a bit more in depth ipython configuration

ipython auto import examples

pyflyby can import all the various import types just fine.

  • import something
  • from module import something
  • import something as alias 
df = pd.read_csv("https://waylonwalker.com/cars.csv")
[PYFLYBY] import pandas as pd
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Getting Help

Want help on something that you have in your pyflyby config, just give it the ?, ??, or help and pyflyby will import it for you.

Popen?
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article cover for Just Ask Ipython for help

this article has more ways to get help in ipython.

Autocomplete

This is next level python auto-import

pyflyby even goes as far as helping tab completion. If you try to tab complete Pop it will complete to Popen without even adding Popen to your local namespace. If you ask for something inside of a module i.e. requests.<tab>, then it will import requests.

# does not populate the namespace
Pop<tab>

# !!does populate the local namespace
requests.<tab>
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What happens when a module is not installed

ModuleNotFoundError

When you are in an environment where you do not have a module installed that is in your pyflyby config, it will throw a ModuleNotFoundError when it tries to import and it will not import or try to install for you. You will have to change environments or install that module.

❯ pd?
[PYFLYBY] import pandas as pd
[PYFLYBY] Error attempting to 'import pandas as pd': ModuleNotFoundError: No module named 'pandas'
[PYFLYBY] Traceback (most recent call last):
[PYFLYBY]   File "/home/u_walkews/.local/lib/python3.8/site-packages/pyflyby/_autoimp.py", line 1610, in _try_import
[PYFLYBY]     exec_(stmt, scratch_namespace)
[PYFLYBY]   File "<string>", line 1, in <module>
[PYFLYBY] ModuleNotFoundError: No module named 'pandas'
Object `pd` not found.

❯ df = pd.read_csv("https://waylonwalker.com/cars.csv")
<ipython-input-3-69b040434562>:1 in <module>

NameError: name 'pd' is not defined
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nvim pyflyby setup

automatically importing python modules in vim, neovim, nvim

This is by far the best part of this article. It makes development so fluid. It's not necessarily all about the speed. It really helps you move at the speed of your thoughts, without needing to worry about imports. Remembering where deeply nested modules are does not need to be a thing.

function! s:PyPreSave()
    Black
endfunction

function! s:PyPostSave()
    execute "silent !tidy-imports --black --quiet --replace-star-imports --action REPLACE " . bufname("%")
    execute "e"
endfunction

:command! PyPreSave :call s:PyPreSave()
:command! PyPostSave :call s:PyPostSave()

augroup waylonwalker
    autocmd!
    autocmd bufwritepre *.py execute 'PyPreSave'
    autocmd bufwritepost *.py execute 'PyPostSave'
    autocmd bufwritepost .tmux.conf execute ':!tmux source-file %'
    autocmd bufwritepost .tmux.local.conf execute ':!tmux source-file %'
    autocmd bufwritepost *.vim execute ':source %'
augroup end
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refactoring

This is where it really shines

This setup really shines when you are refactoring. You can freely move modules and classes around without worrying about bringing imports with them. Often when refactoring some modules from one file to another the most tedious part is editing the imports. Often you can't even grab whole lines because there are several imports and some are needed in both places but not all. pyflyby handles all this like a champ.

Where to install for vim

just make sure the tidy-imports command is available to vim

pyflyby goes into the environment that you have active at the time that you start neovim. Typically this is the virtual environment that I am using for the project I am editing.

What gets imported/removed

only give me what I actually use

Anything within the base config of pyflyby or your own config specified in ~/.pyflyby will get automatically imported if it is used within the file/console. If you are working in a file, and stop using a module, it will automatically get removed.

  • Anything that is used, and found in the config is added
  • Anything that is unused gets removed

Where does it put imports

after the last import

pyflyby does not sort imports into paragraphs or by category. When it needs to add new imports. It will find the last paragraph of imports in your file, add the new one, and sort that paragraph alphebetically.

from collections import Counter

import requests

from plugins.custom_seo import post_render
# <-- pyflyby will put the import here
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What about isort

put those imports where they go

I did not like that I was getting pre-commit issues when using pyflyby, so I added isort to my chain of autocommands to automatically run isort and make my pre-commit happy.

function! s:PyPostSave()
    execute "silent !tidy-imports --black --quiet --replace-star-imports --action REPLACE " . bufname("%")
    execute "silent !isort " . bufname("%")
    execute "e"
endfunction
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Let's write some code

def get():
    """
    Get all the posts from waylonwalker.com.

    Yes theres an rss feed, you should be subscribed if your not already.

    Oh, and we don't need no stinkin error handing because it's always live
    """
    r = requests.get("https://waylonwalker.com/rss")
    return r.content
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Save it and pyflyby will inject requests into our file automatically, no need to type that out anymore.

import requests

def get():
    """
    Get all the posts from waylonwalker.com.

    Yes theres an rss feed, you should be subscribed if your not already.

    Oh, and we don't need no stinkin error handing because it's always live
    """
    r = requests.get("https://waylonwalker.com/rss")
    return r.content
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What about init / api's

careful to fill in the `all` like you are supposed to

Files such as init.py often import things they do not need, this is simply there for a convenience of the library user and to make the api cleaner. These type of modules should implement a __all__ list of all the unused things that are imported according to pep8. Pyflyby will remove any unused modules unless they are in the __all__ list.

# snippet from kedro.extras.datasets.pandas

__all__ = [
    "CSVDataSet",
    "ExcelDataSet",
    "FeatherDataSet",
    "GBQTableDataSet",
    "ExcelDataSet",
    "AppendableExcelDataSet",
    "HDFDataSet",
    "JSONDataSet",
    "ParquetDataSet",
    "SQLQueryDataSet",
    "SQLTableDataSet",
]
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py command

one liners that need imports

pyflyby also comes with a cli command to run one liners. It's pretty genious, I'm sure I will find a use or two for it, but so far its been more of a novelty for me.

py help pd
py help pd.DataFrame

py pd.read_csv 'https://waylonwalker.com/cars.csv'
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Links

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waylonwalker
Waylon Walker

Posted on December 21, 2021

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Smoother Python with automatic imports | pyflyby
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