optutils .02.4

Small, composable utilities for writing great command line tools.

optutils
========

Small, composable utilities for writing great command line tools. Writing
a great command line tool takes art as well as science. Unlike libraries and
frameworks, commandline tools are used interactively by the programmer.
Therefore, their input interface must be forgiving yet consistent, their output
must be computer parsable yet human readable, and their error messages must be
terse yet informative.

#### `Optutils` philosophy:

1. Fail fast -- give the user immediate feedback on what they did wrong.
2. Testable Errors -- provide consistent unique exit status codes to ensure
future testability.
3. Informative Errors -- point the way to the narrow path.
4. Separate Feedback and Output -- feedback for humans should go on the standard
error, output for programs to the standard out.
5. Prioritize Clarity over Code -- the user experience should be paramount, not
the programmer's experience. These utilities are not always designed to make
the text of the program shorter, they are designed to make the user
experience *better*.
6. Every Child is Special -- every utility is just a little different and one
size fits all solutions tend to fit no one. Utilities should therefore be
specialized *yet* re-usable.

# A Minimal Optutils Program with a Subcommand

```python
#!/usr/bin/env python
# -*- coding: utf-8 -*-
#Author: Tim Henderson
#Email: [e-mail], [e-mail]
#For licensing see the LICENSE file in the top level directory.


import os, sys, json

import optutils
from optutils import output, log, error_codes, add_code


__version__ = 'git master'

add_code('version')

def version():
'''Print version and exits'''
log('version :', __version__)
sys.exit(error_codes['version'])


@optutils.main(
'usage: example <command>',
'''
Example:

$ example command what

Options
-h, help print this message
-v, version print the version
''',
'hv',
['help', 'version'],
)
def main(argv, util, parser):
"""
The main entry point to the program
"""

@util.command(
'usage: command [args]',
'''
Example:

Options
-h, help print this message
''',
'h',
['help',],
)
def command(argv, util, parser, setting):

opts, args = parser(argv)
for opt, arg in opts:
if opt in ('-h', '--help',):
util.usage()

print ' '.join(args)
print 'running with', setting


opts, args = parser(argv)
for opt, arg in opts:
if opt in ('-h', '--help',):
util.usage()
elif opt in ('-v', '--version',):
version()

setting = 'wizards'

util.run_command(args, setting)

if __name__ == '__main__':
sys.exit(main(sys.argv[1:]))
```