From bd1c6660079398a406d2160dd6869ea2bb9b25d0 Mon Sep 17 00:00:00 2001
From: Todd Leonhardt <todd.leonhardt@gmail.com>
Date: Sun, 3 Nov 2019 18:03:48 -0500
Subject: Improved documentation for Argument Parsing and Tab-Completion

Also:
- Added a couple examples
---
 docs/features/argument_processing.rst | 24 +++++++++++++++---
 docs/features/completion.rst          | 46 +++++++++++++++++++++++++++++++++++
 2 files changed, 66 insertions(+), 4 deletions(-)

(limited to 'docs')

diff --git a/docs/features/argument_processing.rst b/docs/features/argument_processing.rst
index a3d4a3aa..a8124292 100644
--- a/docs/features/argument_processing.rst
+++ b/docs/features/argument_processing.rst
@@ -1,5 +1,3 @@
-.. _decorators:
-
 Argument Processing
 ===================
 
@@ -33,6 +31,7 @@ applications.
 .. _argprint: https://github.com/python-cmd2/cmd2/blob/master/examples/arg_print.py
 .. _decorator: https://github.com/python-cmd2/cmd2/blob/master/examples/decorator_example.py
 
+.. _decorators:
 
 Decorators provided by cmd2 for argument processing
 ---------------------------------------------------
@@ -40,12 +39,12 @@ Decorators provided by cmd2 for argument processing
 ``cmd2`` provides the following decorators for assisting with parsing arguments
 passed to commands:
 
-.. automethod:: cmd2.decorators.with_argument_list
-   :noindex:
 .. automethod:: cmd2.decorators.with_argparser
    :noindex:
 .. automethod:: cmd2.decorators.with_argparser_and_unknown_args
    :noindex:
+.. automethod:: cmd2.decorators.with_argument_list
+   :noindex:
 
 All of these decorators accept an optional **preserve_quotes** argument which
 defaults to ``False``. Setting this argument to ``True`` is useful for cases
@@ -342,3 +341,20 @@ use subcommands in your ``cmd2`` application.
 
 .. _subcommands: https://github.com/python-cmd2/cmd2/blob/master/examples/subcommands.py
 .. _tab_autocompletion: https://github.com/python-cmd2/cmd2/blob/master/examples/tab_autocompletion.py
+
+
+Argprase Extensions
+-------------------
+
+``cmd2`` augments the standard ``argparse.nargs`` with range tuple capability:
+
+- ``nargs=(5,)`` - accept 5 or more items
+- ``nargs=(8, 12)`` - accept 8 to 12 items
+
+``cmd2`` also provides the ``Cmd2ArgumentParser`` class which inherits from
+``argparse.ArgumentParser`` and improves error and help output:
+
+.. autoclass:: cmd2.argparse_custom.Cmd2ArgumentParser
+    :members:
+
+
diff --git a/docs/features/completion.rst b/docs/features/completion.rst
index 5d2a722c..dfeddb27 100644
--- a/docs/features/completion.rst
+++ b/docs/features/completion.rst
@@ -31,3 +31,49 @@ similar to the following to your class which inherits from ``cmd2.Cmd``::
 
     # Make sure you have an "import functools" somewhere at the top
     complete_bar = functools.partialmethod(cmd2.Cmd.path_complete, path_filter=os.path.isdir)
+
+
+Tab Completion Using Argparse Decorators
+----------------------------------------
+
+When using one the Argparse-based :ref:`decorators`, ``cmd2`` provides
+automatic tab-completion of flag names.
+
+Tab-completion of argument values can be configured by using one of five
+parameters to ``argparse.ArgumentParser.add_argument()``
+
+- ``choices``
+- ``choices_function`` / ``choices_method``
+- ``completer_function`` / ``completer_method``
+
+See the arg_decorators_ or colors_ example for a demonstration of how to
+use the ``choices`` parameter. See the tab_autocompletion_ example for a
+demonstration of how to use the ``choices_function`` and ``choices_method``
+parameters. See the arg_decorators_ or tab_autocompletion_ example for a
+demonstration of how to use the ``completer_method`` parameter.
+
+When tab-completing flags and/or argument values for a ``cmd2`` command using
+one of these decorators, ``cmd2`` keeps track of state so that once a flag has
+already previously been provided, it won't attempt to tab-complete it again.
+When no completion results exists, a hint for the current argument will be
+displayed to help the user.
+
+.. _arg_decorators: https://github.com/python-cmd2/cmd2/blob/master/examples/arg_decorators.py
+.. _colors: https://github.com/python-cmd2/cmd2/blob/master/examples/colors.py
+.. _tab_autocompletion: https://github.com/python-cmd2/cmd2/blob/master/examples/tab_autocompletion..py
+
+
+CompletionItem For Providing Extra Context
+------------------------------------------
+
+When tab-completing things like a unique ID from a database, it can often be
+beneficial to provide the user with some extra context about the item being
+completed, such as a description.  To facilitate this, ``cmd2`` defines the
+``CompletionItem`` class which can be used in combination with
+``choices_function`` or ``choices_method``.
+
+.. autoclass:: cmd2.argparse_custom.CompletionItem
+    :members:
+
+See the tab_autocompletion_ example or the implementation of the built-in
+**set** command for demonstration of how this is used.
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