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.. _ATTR/ArgParse:
ArgParse
########
Many people use Python's :mod:`argparse` command line argument parser. This parser
can handle sub-commands like ``git commit -m "message"`` where *commit* is a
sub-command and ``-m <message>`` is an argument of this sub-command parser. It's
possible to assign a callback function to each individual sub-command parser.
.. rubric:: Advantages
* Declarative description instead of imperative form.
* All options from argparse can be used.
* Declare accepted command-line arguments close to the responsible handler method
* Complex parsers can be distributed accross multiple classes and merged via multiple inheritance.
* Pre-defined argument templates like switch parameters (``--help``).
.. _ATTR/ArgParse/Comparison:
Comparison
**********
.. grid:: 2
.. grid-item:: **pyTooling.Attributes.ArgParse**
.. code-block:: Python
class Program:
@DefaultHandler()
@FlagArgument(short="-v", long="--verbose", dest="verbose", help="Show verbose messages.")
def HandleDefault(self, args) -> None:
pass
@CommandHandler("new-user", help="Add a new user.")
@StringArgument(dest="username", metaName="username", help="Name of the new user.")
@LongValuedFlag("--quota", dest="quota", help="Max usable disk space.")
def NewUserHandler(self, args) -> None:
pass
@CommandHandler("delete-user", help="Delete a user.")
@StringArgument(dest="username", metaName="username", help="Name of the user.")
@FlagArgument(short="-f", long="--force", dest="force", help="Ignore internal checks.")
def DeleteUserHandler(self, args) -> None:
pass
@CommandHandler("list-user", help="List all users.")
def ListUserHandler(self, args) -> None:
pass
.. grid-item:: **Traditional ArgParse**
.. code-block:: Python
class Program:
def __init__(self):
mainParser = argparse.ArgumentParser()
mainParser.set_defaults(func=self.HandleDefault)
mainParser.add_argument("-v", "--verbose")
subParsers = mainParser.add_subparsers()
newUserParser = subParsers.add_parser("new-user", help="Add a new user.")
newUserParser.add_argument(dest="username", metaName="username", help="Name of the new user.")
newUserParser.add_argument("--quota", dest="quota", help="Max usable disk space.")
newUserParser.set_defaults(func=self.NewUserHandler)
deleteUserParser = subParsers.add_parser("delete-user", help="Delete a user.")
deleteUserParser.add_argument(dest="username", metaName="username", help="Name of the user.")
deleteUserParser.add_argument("-f", "--force", dest="force", help="Ignore internal checks.")
deleteUserParser.set_defaults(func=self.DeleteUserHandler)
listUserParser = subParsers.add_parser("list-user", help="List all users.")
listUserParser.set_defaults(func=self.ListUserHandler)
def HandleDefault(self, args) -> None:
pass
def NewUserHandler(self, args) -> None:
pass
def DeleteUserHandler(self, args) -> None:
pass
def ListUserHandler(self, args) -> None:
pass
.. _ATTR/ArgParse/Arguments:
Arguments
*********
.. _ATTR/ArgParse/Flags:
Flags
=====
.. _ATTR/ArgParse/ValuedFlags:
ValuedFlags
===========
.. _ATTR/ArgParse/ValuedTupleFlags:
ValuedTupleFlags
================
.. _ATTR/ArgParse/Lists:
Argument Lists
**************
.. _ATTR/ArgParse/Commands:
Commands
********
.. _ATTR/ArgParse/Grouping:
Grouping Arguments
******************
.. _ATTR/ArgParse/MixIn:
Split Handlers into multiple classes
************************************
Classic ``argparse`` Example
****************************
.. literalinclude:: ../../tests/example/OldStyle.py
:language: python
:linenos:
:caption: tests/example/OldStyle.py
:tab-width: 2
New ``pyTooling.Attributes`` Approach
*************************************
A better and more descriptive solution could look like this:
.. literalinclude:: ../../tests/example/UserManager.py
:language: python
:linenos:
:caption: tests/example/UserManager.py
:tab-width: 2
.. _ATTR/ArgParse/Consumers:
Consumers
*********
This package is used by:
* ✅ . |br|
:ref:`pyTooling.Attributes.ArgParse <ATTR/ArgParse>`
|
