arghelper 0.1

# arghelper

[![Build Status][travis image]][travis link]
[![PyPi Version][pypi ver image]][pypi ver link]

arghelper is a Python package that provides functions to help with
argparse.

## Requirements

- `argparse` module from the [Python Standard Library][]
- `os` module from the [Python Standard Library][]

## Usage

`arghelper` provides functions to determine if a file or directory
exists:

- `extant_file`
- `extant_dir`

These can be used as follows:

```python
if __name__ == "__main__":
# Process the arguments
import argparse
import arghelper
parser = argparse.ArgumentParser(
description='Process the TAFFmat CET files')
parser.add_argument(
'config_file',
help='CSV configuration file.',
metavar='FILE', type=arghelper.extant_file)
parser.add_argument(
'input_dir',
help='Directory containing input files.',
metvar='DIR', type=arghelper.extant_dir)
args = parser.parse.args()
```

A common pattern, for me at least, is to have three positional arguments
consisting of:

1. `config_file` --- A configuration file
2. `input_dir` --- A directory containing input files to be read
3. `output_dir` --- A directory where the output files should be saved

This pattern has been abstracted to a Facade function called
`parse_config_input_output`, which can be used as follows:

```python
if __name__ == "__main__":
# Process the arguments
import arghelper
args = arghelper.parse_config_input_output(sys.argv)
```

## Contributing

[arghelper][] is developed using [Scott Chacon][]'s [GitHub Flow][]. To
contribute, fork [arghelper][], create a feature branch, and then submit
a pull request. [GitHub Flow][] is summarized as:

- Anything in the `master` branch is deployable
- To work on something new, create a descriptively named branch off of
`master` (e.g., `new-oauth2-scopes`)
- Commit to that branch locally and regularly push your work to the same
named branch on the server
- When you need feedback or help, or you think the brnach is ready for
merging, open a [pull request][].
- After someone else has reviewed and signed off on the feature, you can
merge it into master.
- Once it is merged and pushed to `master`, you can and *should* deploy
immediately.

# License

[arghelper][] is released under the MIT license. Please see the
[LICENSE.txt][] file for more information.

[arghelper]: https://github.com/matthewrankin/arghelper
[github flow]: http://scottchacon.com/2011/08/31/github-flow.html
[LICENSE.txt]: https://github.com/matthewrankin/arghelper/blob/develop/LICENSE.txt
[pull request]: https://help.github.com/articles/using-pull-requests
[pypi ver image]:
[pypi ver link]:
[python standard library]: https://docs.python.org/2/library/
[scott chacon]: http://scottchacon.com/about.html
[travis image]: https://travis-ci.org/matthewrankin/arghelper.png?branch=master
[travis link]: https://travis-ci.org/matthewrankin/arghelper