# Python CLI Bandersnatch By Paul Bailey --- ## Choose Your Own Adventure Python Command Line Libraries: - [argparse](https://docs.python.org/3/library/argparse.html) - [click](https://click.palletsprojects.com/en/7.x/) - [fire](https://google.github.io/python-fire/) - Maybe a bonus!! **Vote at: [ppp.wtf/cli](https://ppp.wtf/cli)** --- <iframe width="100%" height="500" src="https://www.ppp.wtf/embed/cli/1/" frameborder="0" style="border: 0"></iframe> <div style="font-size: 40%;"> <a href="#/3">Cart Wheel</a> - <a href="#/5">About Me</a> </div> --- <iframe width="100%" height="500" src="https://www.ppp.wtf/embed/cli/2/" frameborder="0" style="border: 0"></iframe> <div style="font-size: 40%;"> <a href="#/4">Yes</a> - <a href="#/5">No</a> </div> --- ### This isn't Black Mirror <iframe src="https://giphy.com/embed/3oriNZGGY2eNlwj2sE" width="480" height="267" frameBorder="0" class="giphy-embed" allowFullScreen></iframe> <div style="font-size: 40%;"> <a href="#/6">Next &raquo;</a> </div> --- ## About Me - @PizzaPanther (Twitter, Github, etc) - System Architect @ CognitiveSpace.com --- <iframe width="100%" height="500" src="https://www.ppp.wtf/embed/cli/3/" frameborder="0" style="border: 0"></iframe> <div style="font-size: 40%;"> <a href="#/7">argparse</a> - <a href="#/9">click</a> - <a href="#/11">fire</a> </div> --- ## Intro to Argparse https://docs.python.org/3/library/argparse.html <div style="text-align: left"> Pros: - Easier to use - Included in the standard library - Used very often Cons: - Not so elegant </div> --- ### Sample Argparse ```python import argparse def hello(args): greeting = 'Hello' if args.enable_texas: greeting = 'Howdy' for name in args.names: for i in range(0, args.times): print(f'{greeting} {name}') if __name__ == "__main__": parser = argparse.ArgumentParser() parser.add_argument('--times', help='number of hellos', type=int, default=1) parser.add_argument('--enable-texas', action='store_true') parser.add_argument('names', nargs='+', help='names to say hello') args = parser.parse_args() hello(args) ``` <div style="font-size: 40%;"> <a href="#/13">argparse done</a> - <a href="#/9">click left</a> - <a href="#/11">fire left</a> - <a href="#/16">all done</a> </div> --- ## Intro to Click https://click.palletsprojects.com/en/7.x/ <div style="text-align: left"> Pros: - Easy to use decorators - Loads of tools! - Very flexible for many uses cases Cons: - Lots of decorators - Loads of tools to learn </div> --- ### Sample Click ```python import click @click.command() @click.argument('names', nargs=-1) @click.option('--times', default=1, help='number of hellos') @click.option('--enable-texas', is_flag=True) def hello(names, times, enable_texas): greeting = 'Hello' if enable_texas: greeting = 'Howdy' for name in names: for i in range(0, times): print(f'{greeting} {name}') if __name__ == "__main__": hello() ``` <div style="font-size: 40%;"> <a href="#/14">click done</a> - <a href="#/7">argparse left</a> - <a href="#/11">fire left</a> - <a href="#/16">all done</a> </div> --- ### Intro to Fire https://google.github.io/python-fire/ <div style="text-align: left"> Pros: - Easiest to use - Make a CLI out of any Python code Cons: - Non-standard CLI usage - Fewer standard features </div> --- ### Fire Example ```python import fire def hello(names, times=1, enable_texas=False): greeting = 'Hello' if enable_texas: greeting = 'Howdy' for name in names: for i in range(0, times): print(f'{greeting} {name}') if __name__ == "__main__": fire.Fire(hello) ``` <div style="font-size: 40%;"> <a href="#/15">fire done</a> - <a href="#/7">argparse left</a> - <a href="#/9">click left</a> - <a href="#/16">all done</a> </div> --- <iframe width="100%" height="500" src="https://www.ppp.wtf/embed/cli/4/" frameborder="0" style="border: 0"></iframe> <div style="font-size: 40%;"> <a href="#/9">click</a> - <a href="#/11">fire</a> </div> --- <iframe width="100%" height="500" src="https://www.ppp.wtf/embed/cli/5/" frameborder="0" style="border: 0"></iframe> <div style="font-size: 40%;"> <a href="#/7">argparse</a> - <a href="#/11">fire</a> </div> --- <iframe width="100%" height="500" src="https://www.ppp.wtf/embed/cli/6/" frameborder="0" style="border: 0"></iframe> <div style="font-size: 40%;"> <a href="#/7">argparse</a> - <a href="#/9">click</a> </div> --- <iframe width="100%" height="500" src="https://www.ppp.wtf/embed/cli/7/" frameborder="0" style="border: 0"></iframe> <div style="font-size: 40%;"> <a href="#/23">sub-commands</a> - <a href="#/17">click</a> - <a href="#/25">fire</a> </div> --- ### Click Subcommands ```python import click @click.group() @click.option('--times', default=1, help='number of hellos') @click.pass_context def cli(context, times): context.obj['times'] = times def greet(context, greeting, names): for name in names: for i in range(0, context.obj['times']): print(f'{greeting} {name}') @cli.command() @click.pass_context @click.argument('names', nargs=-1) def hello(context, names): greet(context, 'Hello', names) @cli.command() @click.pass_context @click.argument('names', nargs=-1) def howdy(context, names): greet(context, 'Howdy', names) @cli.command() @click.pass_context @click.argument('names', nargs=-1) def all(context, names): context.forward(hello) context.forward(howdy) if __name__ == "__main__": cli(obj={}) ``` --- ### Click Types <div style="font-size: 70%"> https://click.palletsprojects.com/en/7.x/parameters/#parameter-types </div> ```python @click.option( '--cert', type=click.Path(exists=True, dir_okay=False), default=None ) ``` --- ### Click ENVs <div style="font-size: 70%"> https://click.palletsprojects.com/en/7.x/arguments/#environment-variables </div> ```python @click.argument( 'src', envvar='SRC', type=click.File('r') ) ``` --- ### Click Colors ```python click.echo( click.style('Hello World!', fg='green') ) ``` ---  --- ### More Click https://click.palletsprojects.com/en/7.x/utils/ - Clear screen - Getting characters - Waiting for keypress - Launching editors, applications - Progress bars - and More! <div style="font-size: 40%;"> <a href="#/30">Questions/Comments &raquo;</a> </div> --- ### Argparse subcommands ```python= import argparse def howdy(args): _greet('Howdy', args.names, times=args.times) def hello(args): _greet('Hello', args.names, times=args.times) def all(args): hello(args) howdy(args) def _greet(greeting, names, times=1): for name in names: for i in range(0, times): print(f'{greeting} {name}') if __name__ == "__main__": parser = argparse.ArgumentParser(prog='PROG') parser.add_argument('--times', help='number of hellos', type=int, default=1) subparsers = parser.add_subparsers(help='sub-command help', dest='command') parser_hello = subparsers.add_parser('hello', help='say hello') parser_howdy = subparsers.add_parser('howdy', help='say howdy') parser_all = subparsers.add_parser('all', help='say hello and howdy') for p in (parser_hello, parser_howdy, parser_all): p.add_argument('names', nargs='+', help='names to say hello') args = parser.parse_args() globals()[args.command](args) ``` --- ### Click Subcommands ```python import click @click.group() @click.option('--times', default=1, help='number of hellos') @click.pass_context def cli(context, times): context.obj['times'] = times def greet(context, greeting, names): for name in names: for i in range(0, context.obj['times']): print(f'{greeting} {name}') @cli.command() @click.pass_context @click.argument('names', nargs=-1) def hello(context, names): greet(context, 'Hello', names) @cli.command() @click.pass_context @click.argument('names', nargs=-1) def howdy(context, names): greet(context, 'Howdy', names) @cli.command() @click.pass_context @click.argument('names', nargs=-1) def all(context, names): context.forward(hello) context.forward(howdy) if __name__ == "__main__": cli(obj={}) ``` --- ### Fire subcommands (Functional) ```python= import fire def howdy(names, times=1): _greet('Howdy', names, times=times) def hello(names, times=1): _greet('Hello', names, times=times) def all(names, times=1): hello(names, times=times) howdy(names, times=times) def _greet(greeting, names, times=1): for name in names: for i in range(0, times): print(f'{greeting} {name}') if __name__ == "__main__": fire.Fire() ``` --- ### Fire subcommands (Class) ```python= import fire class Greet: def howdy(self, names, times=1): self._greet('Howdy', names, times=times) def hello(self, names, times=1): self._greet('Hello', names, times=times) def all(self, names, times=1): self.hello(names, times=times) self.howdy(names, times=times) def _greet(self, greeting, names, times=1): for name in names: for i in range(0, times): print(f'{greeting} {name}') if __name__ == "__main__": fire.Fire(Greet) ``` --- <iframe width="100%" height="500" src="https://www.ppp.wtf/embed/cli/8/" frameborder="0" style="border: 0"></iframe> <div style="font-size: 40%;"> <a href="#/28">Argparse</a> - <a href="#/29">Docopt</a> </div> --- ### More Argparse <div style="text-align: left; font-size: 90%;"> Number of Args: https://docs.python.org/3/library/argparse.html#nargs Actions: https://docs.python.org/3/library/argparse.html#action File Types: ```python parser.add_argument('out', type=argparse.FileType('w')) ``` </div> <br> <div style="font-size: 40%;"> <a href="#/30">Questions/Comments &raquo;</a> </div> --- ### Bonus: Docopt http://docopt.org/ ```python= """Naval Fate. Usage: naval_fate.py ship new <name>... naval_fate.py ship <name> move <x> <y> [--speed=<kn>] naval_fate.py ship shoot <x> <y> naval_fate.py mine (set|remove) <x> <y> [--moored | --drifting] naval_fate.py (-h | --help) naval_fate.py --version Options: -h --help Show this screen. --version Show version. --speed=<kn> Speed in knots [default: 10]. --moored Moored (anchored) mine. --drifting Drifting mine. """ from docopt import docopt if __name__ == '__main__': arguments = docopt(__doc__, version='Naval Fate 2.0') print(arguments) ``` --- ## Comments and Questions <iframe src="https://giphy.com/embed/lz67zZWfWPsWnuGH0s" width="480" height="360" frameBorder="0" class="giphy-embed" allowFullScreen></iframe> Examples on [Github](https://github.com/pizzapanther/pizzapanther.github.io/tree/master/talks/cli-examples)