commandlines

Commandlines Library Documentation

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Source Repository: chrissimpkins/commandlines <https://github.com/chrissimpkins/commandlines>__

Documentation: commandlines.github.io <https://commandlines.github.io>__

What is Commandlines?

Commandlines <https://github.com/chrissimpkins/commandlines>__ is a Python library for command line application development that supports command line argument parsing, command string validation testing, & application logic. It has no external dependencies and provides broad Python interpreter support for Python 2.6+, Python 3.3+, pypy, and pypy3 across OS X, Linux, and Windows platforms.

The library supports application development with POSIX guideline compliant <https://www.gnu.org/software/libc/manual/html_node/Argument-Syntax.html#Argument-Syntax>__ [*]_ command argument styles, the GNU argument style extensions to the POSIX guidelines <https://www.gnu.org/prep/standards/standards.html#Command_002dLine-Interfaces>__ (including long option syntax and variable position of options among arguments), and command suite style application arguments that include one or more sub-commands to the executable.

.. [*] with the exception of the short single option-argument definition syntax that does not include an intervening space character (e.g. -ofile)

How Do I Use It?

The command line string to your executable script is parsed to multiple objects that are derived from builtin Python types.

The Command Object

Instantiate a ``commandlines`` Command object:

.. code:: python

    from commandlines import Command

    c = Command()

and use the following instance attributes and methods to develop your application:

Arguments
^^^^^^^^^

+-----------------+-----------------------------------+-------------------------------------+
| Command Line    | Command Example                   | Accessed/Tested                     |
| Arguments       |                                   | With                                |
+=================+===================================+=====================================+
| Length of arg   | ``$ spam eggs -t --out file``     | ``c.argc == 4``                     |
| list            |                                   |                                     |
+-----------------+-----------------------------------+-------------------------------------+
| Command suite   | ``$ spam eggs``                   | ``c.subcmd == "eggs"``              |
| sub-commands    |                                   |                                     |
+-----------------+-----------------------------------+-------------------------------------+
| Command suite   | ``$ spam eggs overeasy``          | ``c.subsubcmd == "overeasy"``       |
| sub-sub-commands|                                   |                                     |
|                 |                                   |                                     |
+-----------------+-----------------------------------+-------------------------------------+
| Short switch    | ``$ spam -e``                     | ``c.contains_switches('e')``        |
| syntax          |                                   |                                     |
+-----------------+-----------------------------------+-------------------------------------+
| Long switch     | ``$ spam --eggs``                 | ``c.contains_switches('eggs')``     |
| syntax          |                                   |                                     |
+-----------------+-----------------------------------+-------------------------------------+
| Multiple        | ``$ spam -e --eggs``              | ``c.contains_switches('e', 'eggs')``|
| switches        |                                   |                                     |
|                 |                                   |                                     |
+-----------------+-----------------------------------+-------------------------------------+
| Short opt-arg   | ``$ spam -o eggs``                | ``c.get_definition('o')``           |
| definition      |                                   |                                     |
| syntax          |                                   |                                     |
+-----------------+-----------------------------------+-------------------------------------+
| Long opt-arg    | ``$ spam --out eggs``             | ``c.get_definition('out')``         |
| definition      |                                   |                                     |
| syntax          |                                   |                                     |
+-----------------+-----------------------------------+-------------------------------------+
| Alt long        | ``$ spam --out=eggs``             | ``c.get_definition('out')``         |
| opt-arg         |                                   |                                     |
| definition      |                                   |                                     |
| syntax          |                                   |                                     |
+-----------------+-----------------------------------+-------------------------------------+
| Multiple same   | ``$ spam -o eggs -o omelets``     | ``c.get_multiple_definitions('o')`` |
| option          |                                   |                                     |
| definitions     |                                   |                                     |
+-----------------+-----------------------------------+-------------------------------------+
| Multi-option    | ``$ spam -mpns eggs``             | ``c.contains_mops('m')``            |
| short syntax    |                                   |                                     |
| switches        |                                   |                                     |
+-----------------+-----------------------------------+-------------------------------------+
| Next positional | ``$ spam eggs test/path``         | ``c.get_arg_after('eggs')``         |
| argument        |                                   |                                     |
+-----------------+-----------------------------------+-------------------------------------+

Positional Arguments
^^^^^^^^^^^^^^^^^^^^

Positional arguments use a 0 based index starting at the first argument
to the executable (i.e. ``sys.argv[1:]``) and are maintained as
attributes in the Command object. Individual attribute support is
provided for the first five positional arguments and the last positional
argument. An ordered list of all positional arguments is available in
the ``arguments`` attribute.

+-----------------+----------------------------------------+--------------------+
| Positional      | Command Example                        | Accessed/Tested    |
| Argument        |                                        | With               |
+=================+========================================+====================+
| Positional      | ``$ spam eggs``                        | ``c.arg0``         |
| argument at     |                                        |                    |
| index 0         |                                        |                    |
+-----------------+----------------------------------------+--------------------+
| Positional      | ``$ spam eggs bacon``                  | ``c.arg1``         |
| argument at     |                                        |                    |
| index 1         |                                        |                    |
+-----------------+----------------------------------------+--------------------+
| Positional      | ``$ spam eggs bacon toast``            | ``c.arg2``         |
| argument at     |                                        |                    |
| index 2         |                                        |                    |
+-----------------+----------------------------------------+--------------------+
| Positional      | ``$ spam eggs bacon toast cereal``     | ``c.arg3``         |
| argument at     |                                        |                    |
| index 3         |                                        |                    |
+-----------------+----------------------------------------+--------------------+
| Positional      | ``$ spam eggs bacon toast cereal milk``| ``c.arg4``         |
| argument at     |                                        |                    |
| index 4         |                                        |                    |
+-----------------+----------------------------------------+--------------------+
| Last positional | ``$ spam eggs -b --toast filepath``    | ``c.arglp``        |
| argument        |                                        |                    |
+-----------------+----------------------------------------+--------------------+
| All positional  | ``$ spam eggs -b - -toast filepath``   | ``c.arguments``    |
| arguments       |                                        |                    |
+-----------------+----------------------------------------+--------------------+


Default Option-Argument Definitions
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Define option-argument defaults in a ``defaults`` Command instance
attribute. This attribute is defined as an empty Python dictionary upon
instantiation of the Command object. Use standard key index-based Python
dictionary assignments or the ``set_defaults`` assignment method in the
Command class to define default values. Default values can take any type
that is permissible as a Python dictionary value.

Here are examples of each approach that define defaults for ``output``
and ``level`` options:

Key Index-Based Default Assignments
'''''''''''''''''''''''''''''''''''

.. code:: python

    from commandlines import Command

    c = Command()

    c.defaults['output'] = "test.txt"
    c.defaults['level'] = 10

Method-Based Default Assignments
''''''''''''''''''''''''''''''''

.. code:: python

    from commandlines import Command

    c = Command()

    default_options = {
        'output' : 'test.txt',
        'level'  : 10
    }
    c.set_defaults(default_options)

To test for the presence of a default option definition and obtain its
value, use the ``contains_defaults`` and ``get_default`` methods,
respectively:

.. code:: python

    # continued from code examples above

    if c.contains_definitions('output'):
        dosomething(c.get_definition('output'))
    elif c.contains_defaults('output'):
        dosomething(c.get_default('output'))
    else:
        dosomethingelse()


Help, Usage, and Version Request Testing Methods
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Help, usage, and version command line requests are tested with methods:

+--------------------------+------------------------+------------------------------+
| Test Type                | Command Example        | Tested With                  |
+==========================+========================+==============================+
| Help request, short      | ``$ spam -h``          | ``c.is_help_request()``      |
+--------------------------+------------------------+------------------------------+
| Help request, long       | ``$ spam --help``      | ``c.is_help_request()``      |
+--------------------------+------------------------+------------------------------+
| Usage request            | ``$ spam --usage``     | ``c.is_usage_request()``     |
+--------------------------+------------------------+------------------------------+
| Version request, short   | ``$ spam -v``          | ``c.is_version_request()``   |
+--------------------------+------------------------+------------------------------+
| Version request, long    | ``$ spam --version``   | ``c.is_version_request()``   |
+--------------------------+------------------------+------------------------------+

Testing Methods for Other Commonly Used Switches
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

+---------------------------+-----------------------------+------------------------------+
| Test Type                 | Command Example             | Tested With                  |
+===========================+=============================+==============================+
| Verbose standard output   | ``$ spam eggs --verbose``   | ``c.is_verbose_request()``   |
+---------------------------+-----------------------------+------------------------------+
| Quiet standard output     | ``$ spam eggs --quiet``     | ``c.is_quiet_request()``     |
+---------------------------+-----------------------------+------------------------------+

Special Command Line Idioms
^^^^^^^^^^^^^^^^^^^^^^^^^^^

The double dash idiom escapes all subsequent tokens from option/argument
parsing. Methods are available to determine whether a double dash token
is present in a command and obtain an ordered list of all command line
arguments that follow this idiom:

+-----------------+----------------------------------------+----------------------------------------+
| Command Line    | Command Example                        | Accessed/Tested                        |
| Idioms          |                                        | With                                   |
+=================+========================================+========================================+
| Double dash     | ``$ spam eggs -- -badfile``            | ``c.has_double_dash()``                |
| idiom           |                                        |                                        |
+-----------------+----------------------------------------+----------------------------------------+
| Double dash     | ``$ spam eggs -- -badfile -badfile2``  | ``c.get_double_dash_args()``           |
| arguments       |                                        |                                        |
|                 |                                        |                                        |
+-----------------+----------------------------------------+----------------------------------------+

Application Logic Testing Methods
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

+-----------------+----------------------------------------+--------------------------------------------------------+
| Test Type       | Command Example                        | Tested With                                            |
+=================+========================================+========================================================+
| Positional      | ``$ spam eggs doit``                   | ``c.has_command_sequence('eggs', 'doit')``             |
| command         |                                        |                                                        |
| sequence        |                                        |                                                        |
+-----------------+----------------------------------------+--------------------------------------------------------+
| Single switch   | ``$ spam -s``                          | ``c.contains_switches('s')``                           |
|                 |                                        |                                                        |
+-----------------+----------------------------------------+--------------------------------------------------------+
| Multiple switch | ``$ spam -s --eggs``                   | ``c.contains_switches('s', 'eggs')``                   |
|                 |                                        |                                                        |
+-----------------+----------------------------------------+--------------------------------------------------------+
| Single          | ``$ spam -o eggs``                     | ``c.contains_definitions('o')``                        |
| definition      |                                        |                                                        |
+-----------------+----------------------------------------+--------------------------------------------------------+
| Multiple        | ``$ spam -o eggs --with bacon``        | ``c.contains_definitions('o', 'with')``                |
| different       |                                        |                                                        |
| definitions     |                                        |                                                        |
+-----------------+----------------------------------------+--------------------------------------------------------+
| Multiple same   | ``$ spam -o eggs -o bacon``            | ``c.contains_multi_definitions('o')``                  |
| definitions     |                                        |                                                        |
|                 |                                        |                                                        |
+-----------------+----------------------------------------+--------------------------------------------------------+
| Positional      | ``$ spam eggs --coffee``               | ``c.has_args_after('eggs')``                           |
| argument        |                                        |                                                        |
+-----------------+----------------------------------------+--------------------------------------------------------+
| Acceptable      | ``$ spam eggs toaster``                | ``c.next_arg_is_in('eggs', ['toaster', 'coffeepot'])`` |
| positional arg  |                                        |                                                        |
|                 |                                        |                                                        |
+-----------------+----------------------------------------+--------------------------------------------------------+

Command String Validation Methods
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

+-----------------+-------------------------+----------------------------------------------+
| Test Type       | Failure Example         | Tested With                                  |
+=================+=========================+==============================================+
| Missing         | ``$ spam``              | ``c.does_not_validate_missing_args()``       |
| arguments       |                         |                                              |
|                 |                         |                                              |
+-----------------+-------------------------+----------------------------------------------+
| Expected        | ``$ spam eggs``         | ``c.does_not_validate_n_args(2)``            |
| argument number |                         |                                              |
+-----------------+-------------------------+----------------------------------------------+
| Missing opt-arg | ``$ spam -o --eggs``    | ``c.does_not_validate_missing_defs()``       |
| definitions     |                         |                                              |
|                 |                         |                                              |
+-----------------+-------------------------+----------------------------------------------+
| Missing         | ``$ spam eggs``         | ``c.does_not_validate_missing_switches()``   |
| switches        |                         |                                              |
|                 |                         |                                              |
+-----------------+-------------------------+----------------------------------------------+
| Missing         | ``$ spam -o eggs``      | ``c.does_not_validate_missing_mops()``       |
| multi-option    |                         |                                              |
| short syntax    |                         |                                              |
| switches        |                         |                                              |
+-----------------+-------------------------+----------------------------------------------+


Development with Commandlines

To facilitate development with Commandlines, you can print the string returned by the Command obj_string() method to view a list of the parsed arguments from example commands:

.. code:: python

from commandlines import Command

c = Command()

print(c.obj_string())
sys.exit(0)

For example, if you execute your script with the command spam eggs --toast -b --drink=milk filepath and include the above print statement in your source, you will see the following in your terminal emulator:

.. code:: shell

$ spam eggs --toast -b --drink=milk filepath
obj.argc = 5
obj.arguments = ['eggs', '--toast', '-b', '--drink=milk', 'filepath']
obj.defaults = {}
obj.switches = {'toast', 'b'}
obj.defs = {'drink': 'milk'}
obj.mdefs = {}
obj.mops = {}
obj.arg0 = 'eggs'
obj.arg1 = '--toast'
obj.arg2 = '-b'
obj.arg3 = '--drink=milk'
obj.arg4 = 'filepath'
obj.arglp = 'filepath'
obj.subcmd = 'eggs'
obj.subsubcmd = '--toast'

API Documentation

You can view full documentation of the Command class `here <https://commandlines.github.io/commandlines.library.html#commandlines.library.Command>`__.

If you would like to dig into lower level objects in the commandlines
package, you can view the `library API
documentation <https://commandlines.github.io/commandlines.library.html>`__.

Exceptions that are used in the commandlines package are documented
`here <https://commandlines.github.io/commandlines.exceptions.html>`__.

How to Include Commandlines in Your Project
-------------------------------------------

For Projects That Will Be Distributed to Others

Add the commandlines package dependency to your project setup.py file in the install_requires field like so:

.. code:: python

setup(
    ...
    install_requires=["commandlines"],
    ...
)

Then, enter the following command to test your project locally:

::

$ python setup.py develop

Import the commandlines package in your project and instantiate a Command object by adding the following lines to your Python script:

.. code:: python

from commandlines import Command

c = Command()

And away you go...

The Commandlines package will be installed automatically for users who install your releases via pip or your project setup.py file (i.e. with the command $ python setup.py install).

For Local Projects That Are Not Intended for Redistribution

Install the Commandlines package with the command:

::

    $ pip install commandlines

Import the ``commandlines`` package in your project and instantiate a
Command object by adding the following lines to your Python script:

.. code:: python

    from commandlines import Command

    c = Command()

License
-------

Commandlines is licensed under the `MIT license <https://github.com/chrissimpkins/commandlines/blob/master/docs/LICENSE>`__.




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