docopt-ng 0.7.1

# `docopt-ng` creates *magic* command-line interfaces

[](https://travis-ci.org/bazaar-projects/docopt-ng)

[](https://pypi.python.org/pypi/docopt-ng)

## CHANGELOG

#### New in version 0.7.1:

> - Add `magic()` and `magic_docopt()` aliases for `docopt()` allowing easier use of new features.

#### New in version 0.7.0:

> - "MORE MAGIC"
> - First argument is now optional - `docopt()` will look for `__doc__` defined in parent scopes.
> - Dot access is supported on resulting `arguments` object,
> ignoring angle brackets and leading dashes.
> - `more_magic` parameter added to `docopt()` defaults False.
> - If `more_magic` enabled, `arguments` variable created and populated
> in calling scope with results.
> - If `more_magic` enabled, fuzzy (levenshtein) autocorrect enabled for long-args.
> - Lots of typehints.
> - README moved to Markdown.

#### New in version 0.6.3:

> - Catch up on \~two years of pull requests.
> - Fork [docopt](https://github.com/docopt/docopt) to
> [docopt-ng](https://github.com/bazaar-projects/docopt-ng).
> - Add levenshtein based autocorrect from
> [string-dist](https://github.com/obulkin/string-dist).
> - Add better debug / error messages.
> - Linting (via [black](https://github.com/ambv/black) and
> [flake8](https://gitlab.com/pycqa/flake8)).

#### New in version 0.6.2:

> - Bugfixes
>
#### New in version 0.6.1:
>
> - Fix issue [\#85](https://github.com/docopt/docopt/issues/85) which
> caused improper handling of `[options]` shortcut if it was present
> several times.
>
#### New in version 0.6.0:
>
> - New argument `options_first`, disallows interspersing options and
> arguments. If you supply `options_first=True` to `docopt`, it will
> interpret all arguments as positional arguments after first
> positional argument.
> - If option with argument could be repeated, its default value will
> be interpreted as space-separated list. E.g. with
> `[default: ./here ./there]` will be interpreted as
> `['./here', './there']`.

**docopt-ng** helps you create beautiful command-line interfaces *magically*:

``` {.sourceCode .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)
```

Beat that! The option parser is generated based on the docstring above
that is passed to `docopt` function. `docopt` parses the usage pattern
(`"Usage: ..."`) and option descriptions (lines starting with dash
"`-`") and ensures that the program invocation matches the usage
pattern; it parses options, arguments and commands based on that. The
basic idea is that *a good help message has all necessary information in
it to make a parser*.

Also, [PEP 257](http://www.python.org/dev/peps/pep-0257/) recommends
putting help message in the module docstrings.

# Installation

Use [pip](http://pip-installer.org) or easy\_install:

pip install docopt-ng

Alternatively, you can just drop `docopt.py` file into your project--it
is self-contained.

**docopt-ng** is tested with Python 3.6 and 3.7.

# Testing

You can run unit tests using the command:

> python setup.py test

# API

``` {.sourceCode .python}
from docopt import docopt
```

``` {.sourceCode .python}
docopt(docstring=None, argv=None, help=True, version=None, options_first=False, more_magic=False)
```

`docopt` takes 6 optional arguments:

- `docstring` could be a module docstring (`__doc__`) or some other string
that contains a **help message** that will be parsed to create the
option parser. The simple rules of how to write such a help message
are given in next sections. Here is a quick example of such a
string:

``` {.sourceCode .python}
"""Usage: my_program.py [-hso FILE] [--quiet | --verbose] [INPUT ...]

-h --help show this
-s --sorted sorted output
-o FILE specify output file [default: ./test.txt]
--quiet print less text
--verbose print more text

"""
```
If it is None (not provided) - the calling scope will be interrogated for a docstring.

- `argv` is an optional argument vector; by default `docopt` uses the
argument vector passed to your program (`sys.argv[1:]`).
Alternatively you can supply a list of strings like
`['--verbose', '-o', 'hai.txt']`.
- `help`, by default `True`, specifies whether the parser should
automatically print the help message (supplied as `doc`) and
terminate, in case `-h` or `--help` option is encountered (options
should exist in usage pattern, more on that below). If you want to
handle `-h` or `--help` options manually (as other options), set
`help=False`.
- `version`, by default `None`, is an optional argument that specifies
the version of your program. If supplied, then, (assuming
`--version` option is mentioned in usage pattern) when parser
encounters the `--version` option, it will print the supplied
version and terminate. `version` could be any printable object, but
most likely a string, e.g. `"2.1.0rc1"`.

> Note, when `docopt` is set to automatically handle `-h`, `--help`
> and `--version` options, you still need to mention them in usage
> pattern for this to work. Also, for your users to know about them.

- `options_first`, by default `False`. If set to `True` will disallow
mixing options and positional argument. I.e. after first positional
argument, all arguments will be interpreted as positional even if
the look like options. This can be used for strict compatibility
with POSIX, or if you want to dispatch your arguments to other
programs.

- `more_magic`, by default `False`. If set to `True` more advanced
efforts will be made to correct `--long_form` arguments, ie:
`--hlep` will be corrected to `--help`. Additionally, if not
already defined, the variable `arguments` will be created and populated
in the calling scope. `more_magic` is also set True if `docopt()` is
is aliased to a name containing `magic` ie) by built-in`from docopt import magic` or
user-defined `from docopt import docopt as magic_docopt_wrapper` for convenience.

The **return** value is a simple dictionary with options, arguments and
commands as keys, spelled exactly like in your help message. Long
versions of options are given priority. Furthermore, dot notation is
supported, with preceeding dashes (`-`) and surrounding brackets (`<>`)
ignored. For example, if you invoke the top example as:

naval_fate.py ship Guardian move 100 150 --speed=15

the return dictionary will be:

``` {.sourceCode .python}
{'--drifting': False, 'mine': False,
'--help': False, 'move': True,
'--moored': False, 'new': False,
'--speed': '15', 'remove': False,
'--version': False, 'set': False,
'<name>': ['Guardian'], 'ship': True,
'<x>': '100', 'shoot': False,
'<y>': '150'}
```

...and properties can be accessed with `arguments.drifting` or `arguments.x`.

# Help message format

Help message consists of 2 parts:

- Usage pattern, e.g.:

Usage: my_program.py [-hso FILE] [--quiet | --verbose] [INPUT ...]

- Option descriptions, e.g.:

-h --help show this
-s --sorted sorted output
-o FILE specify output file [default: ./test.txt]
--quiet print less text
--verbose print more text

Their format is described below; other text is ignored.

## Usage pattern format

**Usage pattern** is a substring of `doc` that starts with `usage:`
(case *insensitive*) and ends with a *visibly* empty line. Minimum
example:

``` {.sourceCode .python}
"""Usage: my_program.py

"""
```

The first word after `usage:` is interpreted as your program's name. You
can specify your program's name several times to signify several
exclusive patterns:

``` {.sourceCode .python}
"""Usage: my_program.py FILE
my_program.py COUNT FILE

"""
```

Each pattern can consist of the following elements:

- **&lt;arguments&gt;**, **ARGUMENTS**. Arguments are specified as
either upper-case words, e.g. `my_program.py CONTENT-PATH` or words
surrounded by angular brackets: `my_program.py <content-path>`.
- **--options**. Options are words started with dash (`-`), e.g.
`--output`, `-o`. You can "stack" several of one-letter options,
e.g. `-oiv` which will be the same as `-o -i -v`. The options can
have arguments, e.g. `--input=FILE` or `-i FILE` or even `-iFILE`.
However it is important that you specify option descriptions if you
want your option to have an argument, a default value, or specify
synonymous short/long versions of the option (see next section on
option descriptions).
- **commands** are words that do *not* follow the described above
conventions of `--options` or `<arguments>` or `ARGUMENTS`, plus two
special commands: dash "`-`" and double dash "`--`" (see below).

Use the following constructs to specify patterns:

- **\[ \]** (brackets) **optional** elements. e.g.:
`my_program.py [-hvqo FILE]`
- **( )** (parens) **required** elements. All elements that are *not*
put in **\[ \]** are also required, e.g.:
`my_program.py --path=<path> <file>...` is the same as
`my_program.py (--path=<path> <file>...)`. (Note, "required options"
might be not a good idea for your users).
- **|** (pipe) **mutually exclusive** elements. Group them using **(
)** if one of the mutually exclusive elements is required:
`my_program.py (--clockwise | --counter-clockwise) TIME`. Group them
using **\[ \]** if none of the mutually-exclusive elements are
required: `my_program.py [--left | --right]`.
- **...** (ellipsis) **one or more** elements. To specify that
arbitrary number of repeating elements could be accepted, use
ellipsis (`...`), e.g. `my_program.py FILE ...` means one or more
`FILE`-s are accepted. If you want to accept zero or more elements,
use brackets, e.g.: `my_program.py [FILE ...]`. Ellipsis works as a
unary operator on the expression to the left.
- **\[options\]** (case sensitive) shortcut for any options. You can
use it if you want to specify that the usage pattern could be
provided with any options defined below in the option-descriptions
and do not want to enumerate them all in usage-pattern.
- "`[--]`". Double dash "`--`" is used by convention to separate
positional arguments that can be mistaken for options. In order to
support this convention add "`[--]`" to your usage patterns.
- "`[-]`". Single dash "`-`" is used by convention to signify that
`stdin` is used instead of a file. To support this add "`[-]`" to
your usage patterns. "`-`" acts as a normal command.

If your pattern allows to match argument-less option (a flag) several
times:

Usage: my_program.py [-v | -vv | -vvv]

then number of occurrences of the option will be counted. I.e.
`args['-v']` will be `2` if program was invoked as `my_program -vv`.
Same works for commands.

If your usage patterns allows to match same-named option with argument
or positional argument several times, the matched arguments will be
collected into a list:

Usage: my_program.py <file> <file> --path=<path>...

I.e. invoked with
`my_program.py file1 file2 --path=./here --path=./there` the returned
dict will contain `args['<file>'] == ['file1', 'file2']` and
`args['--path'] == ['./here', './there']`.

## Option descriptions format

**Option descriptions** consist of a list of options that you put below
your usage patterns.

It is necessary to list option descriptions in order to specify:

- synonymous short and long options,
- if an option has an argument,
- if option's argument has a default value.

The rules are as follows:

- Every line in `doc` that starts with `-` or `--` (not counting
spaces) is treated as an option description, e.g.:

Options:
--verbose # GOOD
-o FILE # GOOD
Other: --bad # BAD, line does not start with dash "-"

- To specify that option has an argument, put a word describing that
argument after space (or equals "`=`" sign) as shown below. Follow
either &lt;angular-brackets&gt; or UPPER-CASE convention for
options' arguments. You can use comma if you want to separate
options. In the example below, both lines are valid, however you are
recommended to stick to a single style.:

-o FILE --output=FILE # without comma, with "=" sign
-i <file>, --input <file> # with comma, without "=" sign

- Use two spaces to separate options with their informal description:

--verbose More text. # BAD, will be treated as if verbose option had
# an argument "More", so use 2 spaces instead
-q Quit. # GOOD
-o FILE Output file. # GOOD
--stdout Use stdout. # GOOD, 2 spaces

- If you want to set a default value for an option with an argument,
put it into the option-description, in form
`[default: <my-default-value>]`:

--coefficient=K The K coefficient [default: 2.95]
--output=FILE Output file [default: test.txt]
--directory=DIR Some directory [default: ./]

- If the option is not repeatable, the value inside `[default: ...]`
will be interpreted as string. If it *is* repeatable, it will be
splited into a list on whitespace:

Usage: my_program.py [--repeatable=<arg> --repeatable=<arg>]
[--another-repeatable=<arg>]...
[--not-repeatable=<arg>]

# will be ['./here', './there']
--repeatable=<arg> [default: ./here ./there]

# will be ['./here']
--another-repeatable=<arg> [default: ./here]

# will be './here ./there', because it is not repeatable
--not-repeatable=<arg> [default: ./here ./there]

## Examples

We have an extensive list of
[examples](https://github.com/bazaar-projects/docopt-ng/tree/master/examples)
which cover every aspect of functionality of **docopt-ng**. Try them
out, read the source if in doubt.

# Development

We would *love* to hear what you think about **docopt-ng** on our
[issues page](https://github.com/bazaar-projects/docopt-ng/issues)

Make pull requests, report bugs, suggest ideas and discuss
**docopt-ng**.