wrapp 0.5.1

Making a CLI Application by wrapping

wrapp: Making a CLI Application by wrapping

wrapp helps you to make a CLI application without boilerplate of logging & argparse.

INSTALL

pip install wrapp

USAGE

TL;DR

1. Create your Python script under a few rules. To do so, start with wrapp.new.

   wrapp.new > YOURS.py
   

2. Edit YOURS.py as you like.

3. Then you can run your Python script as an CLI app.

   wrapp YOURS.py
   

That's it. Let's enjoy !

Create your Python script under a few rules

By using wrapp.new,

wrapp.new > YOURS.py

you can get a template Python file named YOURS.py.

wrapp.new outputs template code at stdout.

$ cat YOURS.py
#!/usr/bin/env python3
from logging import getLogger


LOG = getLogger(__name__)


def set_logger(parent_name):
    global LOG
    LOG = getLogger(f'{parent_name}.{__name__}')


def add_arguments(parser):
    group = parser.add_argument_group(__name__)
    ...


def main(args):
    ...


# code below is an option.
# if you want to run it as an normal Python script
# (`python THIS_SCRIPT.py`), uncomment it.
# if __name__ == '__main__':
#     import wrapp
#     wrapp.main(add_arguments, main, set_logger)

This template has 1 global variable and 3 functions; LOG, set_logger(), add_arguments(), main().

LOG is the logger in this file. It may be changed in set_logger().

set_logger() is assumed to be called by wrapp. Python logging module has an implicit rule that when a logger name is delimited by ., corresponding loggers form parent-child relationship. e.g. wrapp.module named logger is child of the logger named wrapp. And when you configure the wrapp logger, wrapp.module logger is also configured as same as the wrapp logger.

If your script import some other your modules and you want to configure these modules' loggers as the same settings as this, you can call recursively set_logger().

import your_module2

def set_logger(parent_name):
    global LOG
    LOG = getLogger(f'{parent_name}.{__name__}')
    your_module2.set_logger(parent_name)

See also tests/template.py and tests/sub/template2.py.

add_arguments() is the function to set program arguments. add_arguments() takes 1 argument; parser which is assumed as an instance of argparse.ArgumentParser. However, I don't use a type hint now because of redusing import statements.

add_arguments() is also available recusive calling. See also tests/template.py and tests/sub/template2.py.

main() function is the entry point.

When you run wrapp YOURS.py,

1. [Optional] wrapp call set_logger() and also set its logger.

2. The program arguments are parsed as defined in add_arguments() and stored in the variable named args.

3. All program arguments and options are output to console.

4. Finally, the main(args) is called.

As shown above, wrapp assumes your Python file contains add_arguments(parser) and main(args). set_logger() is optional.

Run your Python script as an CLI app

Assume your Python script is YOURS.py.

wrapp YOURS.py --your-options ...

That is, just replace python to wrapp. Then you can keep your script simple:

• if __name__ == '__main__': is not needed.
• Also you don't need any noisy modules such as argparse, from argparse import ..., from logging import ....

"I want to run it as python my_script.py"

If you want to run your code as an usual Python way, just uncomment last 3 lines of the template.

Then you can run like

python my_script.py --some-option ...

Debugging

When you want to debug your script, run the code like this.

python3 -m pdb -m wrapp YOURS.py --your-options ...

Then the debugging mode (pdb) will be started.

FEATURES

• No dependencies. wrapp only depends on Python standard libraries.

• One file. If you don't need to install other packages at all, just copy src/wrapp/wrapp.py.

  $ cp PATH/TO/wrapp_repo/src/wrapp/wrapp.py ./wrapp
  $ chmod u+x wrapp
  $ ./wrapp.new > YOURS.py
  $ ./wrapp YOURS.py
  

• It's like python-fire. But for wrapp, you don't need to import any other module in your Python code.

• It's trivial but you also run your script without the extension; wrapp YOURS.

LICENSE

MIT License.

BACKGROUNDS

As I wrote tons of Python CLI applications, I noticed that,

• argparse is the best practice to add my program command options.
• logging is not bad if I modify something (format, ...).
• But I noticed that there are many similar lines in my applications. And they make my code more dirty.

Here is my application code pattern. Please note that there is nothing infomative.

#!/usr/bin/env python3
from argparse import ArgumentParser, ArgumentDefaultsHelpFormatter
from logging import getLogger
from pathlib import Path
import logging.config


_LOG = getLogger(__name__)


def add_arguments(parser):
    parser.add_argument(
            'in_file', type=Path,
            help='An input file.')
    parser.add_argument(
            '--out-dir', '-d', type=Path, default=None,
            help='A directory.')


def _main(args):
    _LOG.debug('debug')
    _LOG.info('info')
    _LOG.warning('warning')
    _LOG.error('error')
    _LOG.critical('critical')
    ...


def _parse_args():
    parser = ArgumentParser(formatter_class=ArgumentDefaultsHelpFormatter)
    parser.add_argument('-i', '--input-files', nargs='*', help='input files.')
    args = parser.parse_args()
    logging.config.fileConfig('logging.conf')
    for k,v in vars(args).items():
        _LOG.info('{}= {}'.format(k, v))
    return args


def _print_args(args):
    for k, v in vars(args).items():
        _LOG.info(f'{k}= {v}')


if __name__ == '__main__':
    parser = ArgumentParser(formatter_class=ArgumentDefaultsHelpFormatter)
    add_arguments(parser)
    args = parser.parse_args()
    logging.config.fileConfig('logging.conf')
    _print_args(args)
    _main(args)

So I decided to separate it to 2 files; one is the contents only and the other is a wrappter to make any Python files an CLI app.

Finally, I can make the above code much more simple,

#!/usr/bin/env python3
from logging import getLogger
from pathlib import Path


_LOG = getLogger(__name__)


def add_arguments(parser):
    parser.add_argument(
            'in_file', type=Path,
            help='An input file.')
    parser.add_argument(
            '--out-dir', '-d', type=Path, default=None,
            help='A directory.')


def main(args):
    _LOG.debug('debug')
    _LOG.info('info')
    _LOG.warning('warning')
    _LOG.error('error')
    _LOG.critical('critical')
    ...

It's similar to python-fire.

But when I used the fire, I have to insert from fire import Fire and Fire(your_func). I'd like to remove even such a few code.

Then I'm completly free from noisy modules / code !