4 ms·

I have nothing to directly comment on the tutorial. Just a tangential mention regarding the tedious argument parsing boilerplate in Python, I have found Python

I have nothing to directly comment on the tutorial. Just a tangential mention regarding the tedious argument parsing boilerplate in Python, I have found Python Fire to be much more convenient: https://github.com/google/python-fire https://github.com/google/python-fire It would have shaved off another 15-20 lines from the 503 line example ;-)

lapinot 8y ago
Yeah, i couldn't help but notice the first piece of code is an ugly "switch case". There's a python idiom for this, it's putting your functions in a dictionary and doing something like `cmds_dict.get(args.command, default)(args)`. I guess we all have our religious habits for argument parsing (more of a docopt-er myself).
- rob74 8y ago
  I guess the author wanted the code to also look friendly to people who are not that familiar with Python - everybody understands a switch, while what you are describing would probably puzzle some people...
bibyte 8y ago
Python Fire looks much more concise. But do you know of any other languages that handles argument parsing better then Python ?
- agigao 8y ago
  Clojure.
  - bibyte 8y ago
    Can you please post a hello world example ?
- vbsteven 8y ago
  Installed by default I cannot find any. But pretty much any language with a package manager has sane and easy to use libraries to bang out a small CLI app with subcommands and option parsing in minutes. For example PicoCli in Java, Thor in Ruby and Clap in Rust.
- atoav 8y ago
  Have you tried looking at docopt? There are cases where it is not flexible enough but it is good for quick and dirty little scripts because: * you use the docstring to generate the args. This way you always have a minimum usage that is valid * Argument parsing is a bit more limited than doimg it yourself, but everything you usually need is there * Docopt is exists not only for Python, but many other languages implemented it too.
- singingfish 8y ago
  Perl has the problem of too many ways to do it. I like MooX::Options. Example here: https://metacpan.org/source/GETTY/AquariumHive-0.003/lib/App/AquariumHive.pm https://metacpan.org/source/GETTY/AquariumHive-0.003/lib/App...
mcqueenjordan 8y ago
I'm a huge fan of the Click library. Click => command line interface creation kit. Ironic little name...
eadan 8y ago
When using argparse, I find subparsers [1] useful in these situations. import argparse def add_file(file): print('Added ' + file) def main(): parser = argparse.ArgumentParser() subparsers = parser.add_subparsers(title='Sub Commands') # add parser add_parser = subparsers.add_parser('add', help='Add a file') add_parser.add_argument('file', help='File to add') add_parser.set_defaults(func=lambda args: add_file(args.file)) args = parser.parse_args() args.func(args) [1] https://docs.python.org/3/library/argparse.html#sub-commands https://docs.python.org/3/library/argparse.html#sub-commands
aepiepaey 8y ago
I largely find argparse to be OK apart from a couple of issues. First, it allows the user to abbreviate flags. They can pass --fl and it will be interpreted as --flag, assuming no other flag shares the same prefix. This sucks for maintainability: add a new flag and any abbreviation for a previously existing flag that shares the same prefix will now stop working, breaking user workflows. Since Python 3.5 there's the allow_abbrev parameter that allows disabling this behaviour, but then you also lose the ability to combine multiple single-character flags (so you can't pass e.g. '-Ev' any more, and would have to pass '-E -v' instead[1]. The other issue is that it's tedious to keep all the .add_argument calls readable, while maintaining a reasonable maximum line length. [1]: https://bugs.python.org/issue26967 https://bugs.python.org/issue26967
giancarlostoro 8y ago
Reminds me of CherryPy. An object oriented app can become a web server with a few function decorators (to make them public endpoints). Coincidentally still my favorite Python web framework. https://cherrypy.org/ https://cherrypy.org/
Myrmornis 8y ago
docopt deserves a link in this thread: https://github.com/docopt/docopt https://github.com/docopt/docopt It’s a magical idea if you haven’t seen it. You just write the help text and it automatically creates the argument parsing code.
- gibsjose 8y ago
  Magical is truly the word to describe Docopt. I use it for all Python code I write and have also used the C and C++ variants. I would highly recommend Docopt to anyone writing command-line utilities.
oweiler 8y ago
For Java (or any other JVM language), nothing beats https://picocli.info/ https://picocli.info/. Works well with GraalVM, too.
- justbaker 8y ago
  Nice! Thanks for sharing.

lapinot 8y ago

Yeah, i couldn't help but notice the first piece of code is an ugly "switch case". There's a python idiom for this, it's putting your functions in a dictionary and doing something like `cmds_dict.get(args.command, default)(args)`. I guess we all have our religious habits for argument parsing (more of a docopt-er myself).

rob74 8y ago
I guess the author wanted the code to also look friendly to people who are not that familiar with Python - everybody understands a switch, while what you are describing would probably puzzle some people...

bibyte 8y ago

Python Fire looks much more concise. But do you know of any other languages that handles argument parsing better then Python ?

agigao 8y ago
Clojure.
- bibyte 8y ago
  Can you please post a hello world example ?
vbsteven 8y ago
Installed by default I cannot find any. But pretty much any language with a package manager has sane and easy to use libraries to bang out a small CLI app with subcommands and option parsing in minutes. For example PicoCli in Java, Thor in Ruby and Clap in Rust.
atoav 8y ago
Have you tried looking at docopt? There are cases where it is not flexible enough but it is good for quick and dirty little scripts because: * you use the docstring to generate the args. This way you always have a minimum usage that is valid * Argument parsing is a bit more limited than doimg it yourself, but everything you usually need is there * Docopt is exists not only for Python, but many other languages implemented it too.
singingfish 8y ago
Perl has the problem of too many ways to do it. I like MooX::Options. Example here: https://metacpan.org/source/GETTY/AquariumHive-0.003/lib/App/AquariumHive.pm https://metacpan.org/source/GETTY/AquariumHive-0.003/lib/App...

mcqueenjordan 8y ago

I'm a huge fan of the Click library. Click => command line interface creation kit. Ironic little name...

eadan 8y ago

When using argparse, I find subparsers [1] useful in these situations. import argparse def add_file(file): print('Added ' + file) def main(): parser = argparse.ArgumentParser() subparsers = parser.add_subparsers(title='Sub Commands') # add parser add_parser = subparsers.add_parser('add', help='Add a file') add_parser.add_argument('file', help='File to add') add_parser.set_defaults(func=lambda args: add_file(args.file)) args = parser.parse_args() args.func(args) [1] https://docs.python.org/3/library/argparse.html#sub-commands https://docs.python.org/3/library/argparse.html#sub-commands

aepiepaey 8y ago

I largely find argparse to be OK apart from a couple of issues. First, it allows the user to abbreviate flags. They can pass --fl and it will be interpreted as --flag, assuming no other flag shares the same prefix. This sucks for maintainability: add a new flag and any abbreviation for a previously existing flag that shares the same prefix will now stop working, breaking user workflows. Since Python 3.5 there's the allow_abbrev parameter that allows disabling this behaviour, but then you also lose the ability to combine multiple single-character flags (so you can't pass e.g. '-Ev' any more, and would have to pass '-E -v' instead[1]. The other issue is that it's tedious to keep all the .add_argument calls readable, while maintaining a reasonable maximum line length. [1]: https://bugs.python.org/issue26967 https://bugs.python.org/issue26967

giancarlostoro 8y ago

Reminds me of CherryPy. An object oriented app can become a web server with a few function decorators (to make them public endpoints). Coincidentally still my favorite Python web framework. https://cherrypy.org/ https://cherrypy.org/

Myrmornis 8y ago

docopt deserves a link in this thread: https://github.com/docopt/docopt https://github.com/docopt/docopt It’s a magical idea if you haven’t seen it. You just write the help text and it automatically creates the argument parsing code.

gibsjose 8y ago
Magical is truly the word to describe Docopt. I use it for all Python code I write and have also used the C and C++ variants. I would highly recommend Docopt to anyone writing command-line utilities.

oweiler 8y ago

For Java (or any other JVM language), nothing beats https://picocli.info/ https://picocli.info/. Works well with GraalVM, too.

justbaker 8y ago
Nice! Thanks for sharing.