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Double Click - Continue Building Better CLIs
Seb
November 18, 2017
Technology
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Double Click - Continue Building Better CLIs
Seb
November 18, 2017
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Transcript
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Double Click Continue Building Better CLIs Sebastian Vetter @elbaschid Slides:
bit.ly/pyconca-double-click
2
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Check Out Click - Part I Click - A Pleasure
To Write, A Pleasure To Use (PyCon US 2016)
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Seb • @elbaschid • Freelance Coder at Roadside Software •
Outdoor Tour Guide • Vancouver ➡ Rocky Mountains
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Why This Talk?
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Terminology
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Parameter • Argument • Option
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Argument • Mandatory parameter • Only values required What It
Looks Like: $ pgcli postgresql://....
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Option • Optional parameter • Name and value required •
Flags as special options What It Looks Like: $ heroku --help $ heroku logs --app my-heroku-app
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(Sub-)Command • Nested commands allowed • Groups sub-commands • Has
options & arguments What It Looks Like: $ pip install django
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Introducing Click
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click • Author: Armin Ronacher • Version 6.x • http://click.pocoo.org/6/
• Why Click?
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Let's Use It
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pip install click
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Basic Example # cli.py import click @click.command() @click.option('--times', '-t', type=int)
@click.argument('symbol') def main(times, symbol): print(f'I {symbol * times} Click!') if __name__ == '__main__': main()
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Running It $ python test.py -t 5 ❤ I ❤❤❤❤❤
Click!
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Breaking It $ python test.py -t five ❤ Usage: test.py
[OPTIONS] SYMBOL Error: Invalid value for "--times" / "-t": five is not a valid integer
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Predict The Weather
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Using A Web API
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Github Repos • Click Template: bit.ly/click-template • Example Code: bit.ly/double-click-example
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We Are Building • weather config • weather forecast LOCATION
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weather config $ weather config Please enter your API key
[]: mysecretapikey $ cat ~/.weather.cfg mysecretapikey
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weather forecast $ weather forecast Montreal Time Description Min Temp
Max Temp ============================================================ Tue, Nov 14 @ 00h clear sky -2.3 2.1 Tue, Nov 14 @ 03h clear sky -2.8 0.1 Tue, Nov 14 @ 06h few clouds -2.7 -1.2 Tue, Nov 14 @ 09h few clouds -2.9 -2.9 ... ... ... ...
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Multiple Commands
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Group import click @click.command() def main(): pass
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Group import click @click.group() def main(): pass
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config Command @click.command() def config(): pass
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config Command @main.command() def config(): pass
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forecast Command @main.command() @click.argument('location') def forecast(location): pass
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Store The API Key
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Running It $ weather config Please enter your API key
[]: mysecretapikey $ cat ~/.weather.cfg mysecretapikey
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Parameter Types
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Basic Types Click Types int UUID float File str Path
bool Choice IntRange
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Using The Path Type @main.option( '--config-file', type=click.Path(), default=os.path.expanduser('~/.weather.cfg')) @click.option('--api-key', envvar='API_KEY',
default='') def config(config_file, api_key): ...
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Using The Path Type @main.option( '--config-file', type=click.Path(exists=True, writable=True), default=os.path.expanduser('~/.weather.cfg')) @click.option('--api-key',
envvar='API_KEY', default='') def config(config_file, api_key): ...
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Save The Key def config(config_file, api_key): api_key = click.prompt( 'Please
enter your API key', default=api_key ) with open(config_file, 'w') as cfg: cfg.write(api_key)
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Look At The Weather
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weather forecast <name> $ weather forecast Montreal Time Description Min
Temp Max Temp ============================================================ Tue, Nov 14 @ 00h clear sky -2.3 2.1 Tue, Nov 14 @ 03h clear sky -2.8 0.1 Tue, Nov 14 @ 06h few clouds -2.7 -1.2 Tue, Nov 14 @ 09h few clouds -2.9 -2.9 ... ... ... ... API Call https://api.openweathermap.org/data/2.5/forecast?q=Montreal
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weather forecast <city ID> $ weather forecast 6077243 Time Description
Min Temp Max Temp ============================================================ Tue, Nov 14 @ 00h clear sky -2.3 2.1 Tue, Nov 14 @ 03h clear sky -2.8 0.1 Tue, Nov 14 @ 06h few clouds -2.7 -1.2 Tue, Nov 14 @ 09h few clouds -2.9 -2.9 ... ... ... ... API Call https://api.openweathermap.org/data/2.5/forecast?id=6077243
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Custom Parameter Type
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The Return Type from collections import namedtuple Location = namedtuple('Location',
['query', 'value'])
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Our Location Type class LocationType(click.ParamType): name = 'location' def convert(self,
value, param, ctx): try: value = int(value) except ValueError: query = 'q' else: query = 'id' return Location(query, value)
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Use It @main.command() @click.argument('location', type=LocationType()) def forecast(location): ... url =
'https://api.openweathermap.org/data/2.5/forecast' params = { location.query: location.value, } response = session.get(url, params=params) ...
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weather forecast $ weather forecast Montreal Time Description Min Temp
Max Temp ============================================================ Tue, Nov 14 @ 00h clear sky -2.3 2.1 Tue, Nov 14 @ 03h clear sky -2.8 0.1 Tue, Nov 14 @ 06h few clouds -2.7 -1.2 Tue, Nov 14 @ 09h few clouds -2.9 -2.9 ... ... ... ...
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Don't Break It
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The Test Runner from click.testing import CliRunner def test_writing_config_file(): runner
= CliRunner() runner.invoke( main, ['config'], input='mysecretapikey', ) ...
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Filesystem Tests with runner.isolated_filesystem() as env: api_key = '00ee52f44f3350c73f2684a0f23f2805' filename
= f'{env}/weather.cfg' result = runner.invoke( main, ['--config-file', filename, 'config'], input=api_key, )
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The Result assert result.exit_code == 0 assert api_key in result.output
with open(filename) as cfg_file: assert cfg_file.read() == api_key
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Packaging Your CLI
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Learn More • PyPA Packaging User Guide • Grug make
fire! Grug make wheel! - Russell Keith-Magee • Shipping Software To Users With Python - Glyph
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Choose A License It's a minefield, people. All I'm saying
is this: the next time you release code into the wild, do your fellow developers a favor and pick a license – any license. — Coding Horror
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Start With Here # setup.py setup( name='double-click-weather', version='0.0.1', license='MIT', ...
)
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Create The Executable # setup.py setup( ... entry_points={'console_scripts': [ 'weather
= forecast.simple:main']}, ... )
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pip install double-click-weather
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File Location ${VENV}/bin/weather.py
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Generated Code #!${VENV}/bin/python3 # EASY-INSTALL-ENTRY-SCRIPT: 'double-click-weather','console_scripts','weather' __requires__ = 'double-click-weather' import
re import sys from pkg_resources import load_entry_point if __name__ == '__main__': sys.argv[0] = re.sub(r'(-script\.pyw?|\.exe)?$', '', sys.argv[0]) sys.exit( load_entry_point('double-click-weather', 'console_scripts', 'weather')() )
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You Have Many New Tools
57
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PyCascades 2018 Vancouver, BC ! 22-23 January, 2018 ! Get
Your Ticket ! http://www.pycascades.com
58
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None
59
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Need Help Building Cool Let's Talk seb@roadsi.de | www.roadsi.de Slides:
bit.ly/pyconca-double-click Code: bit.ly/double-click-example
60
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Chains & Pipes
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Unix-style Pipeline $ weather find Montreal | weather forecast Time
Description Min Temp Max Temp ============================================================ Tue, Nov 14 @ 00h clear sky -2.3 2.1 Tue, Nov 14 @ 03h clear sky -2.8 0.1 Tue, Nov 14 @ 06h few clouds -2.7 -1.2 ... ... ... ...
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Chainable Group @click.group(chain=True) def main(): pass
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Write To stdout @main.command() @click.argument('location', type=LocationType()) @click.argument('output', type=click.File('w'), default='-') def
find(location, output): ... output.write(f"{location.value}")
64
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Read From stdin @main.command() @click.argument('location', type=click.File('r')) def forecast(location): value =
location.read() ...
Seb
elbaschid
reverentgeek
rmw
skipperchong
carmenhchung
keathley
productmarketing
clairelew
thoeni
jcasabona
