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Help
====
From our experience, end users rarely read documentation no matter how high-
quality or useful that documentation might be. So it is important that you
provide good built-in help within your application. Fortunately, ``cmd2``
makes this easy.
Getting Help
------------
``cmd2`` makes it easy for end users of ``cmd2`` applications to get help via
the built-in ``help`` command. The ``help`` command by itself displays a list
of the commands available:
.. code-block:: text
(Cmd) help
Documented commands (use 'help -v' for verbose/'help <topic>' for details):
===========================================================================
alias help ipy py run_pyscript set shortcuts
edit history macro quit run_script shell
The ``help`` command can also be used to provide detailed help for a specific
command:
.. code-block:: text
(Cmd) help quit
Usage: quit [-h]
Exit this application
optional arguments:
-h, --help show this help message and exit
Providing Help
--------------
``cmd2`` makes it easy for developers of ``cmd2`` applications to provide this
help. By default, the help for a command is the docstring for the ``do_*``
method defining the command - e.g. for a command **foo**, that command is
implementd by defining the ``do_foo`` method and the docstring for that method
is the help.
For commands which use one of the ``argparse`` decorators to parse arguments,
help is provided by ``argparse``. See
:ref:`features/argument_processing:Help Messages` for more information.
Occasionally there might be an unusual circumstance where providing static help
text isn't good enough and you want to provide dynamic information in the help
text for a command. To meet this need, if a ``help_foo`` method is defined to
match the ``do_foo`` method, then that method will be used to provide the help
for command **foo**. This dynamic help is only supported for commands which
do not use an ``argparse`` decorator because didn't want different output for
``help cmd`` than for ``cmd -h``.
Categorizing Commands
---------------------
By default, the ``help`` command displays::
Documented commands (use 'help -v' for verbose/'help <topic>' for details):
===========================================================================
alias help ipy py run_pyscript set shortcuts
edit history macro quit run_script shell
If you have a large number of commands, you can optionally group your commands
into categories. Here's the output from the example ``help_categories.py``::
Documented commands (use 'help -v' for verbose/'help <topic>' for details):
Application Management
======================
deploy findleakers redeploy sessions stop
expire list restart start undeploy
Command Management
==================
disable_commands enable_commands
Connecting
==========
connect which
Server Information
==================
resources serverinfo sslconnectorciphers status thread_dump vminfo
Other
=====
alias edit history py run_pyscript set shortcuts
config help macro quit run_script shell version
There are 2 methods of specifying command categories, using the
``@with_category`` decorator or with the ``categorize()`` function. Once a
single command category is detected, the help output switches to a categorized
mode of display. All commands with an explicit category defined default to the
category `Other`.
Using the ``@with_category`` decorator::
@with_category(CMD_CAT_CONNECTING)
def do_which(self, _):
"""Which command"""
self.poutput('Which')
Using the ``categorize()`` function:
You can call with a single function::
def do_connect(self, _):
"""Connect command"""
self.poutput('Connect')
# Tag the above command functions under the category Connecting
categorize(do_connect, CMD_CAT_CONNECTING)
Or with an Iterable container of functions::
def do_undeploy(self, _):
"""Undeploy command"""
self.poutput('Undeploy')
def do_stop(self, _):
"""Stop command"""
self.poutput('Stop')
def do_findleakers(self, _):
"""Find Leakers command"""
self.poutput('Find Leakers')
# Tag the above command functions under the category Application Management
categorize((do_undeploy,
do_stop,
do_findleakers), CMD_CAT_APP_MGMT)
The ``help`` command also has a verbose option (``help -v`` or ``help
--verbose``) that combines the help categories with per-command Help Messages::
Documented commands (use 'help -v' for verbose/'help <topic>' for details):
Application Management
================================================================================
deploy Deploy command
expire Expire command
findleakers Find Leakers command
list List command
redeploy Redeploy command
restart usage: restart [-h] {now,later,sometime,whenever}
sessions Sessions command
start Start command
stop Stop command
undeploy Undeploy command
Connecting
================================================================================
connect Connect command
which Which command
Server Information
================================================================================
resources Resources command
serverinfo Server Info command
sslconnectorciphers SSL Connector Ciphers command is an example of a command that contains
multiple lines of help information for the user. Each line of help in a
contiguous set of lines will be printed and aligned in the verbose output
provided with 'help --verbose'
status Status command
thread_dump Thread Dump command
vminfo VM Info command
Other
================================================================================
alias Manage aliases
config Config command
edit Run a text editor and optionally open a file with it
help List available commands or provide detailed help for a specific command
history View, run, edit, save, or clear previously entered commands
macro Manage macros
py Invoke Python command or shell
quit Exits this application
run_pyscript Runs a python script file inside the console
run_script Runs commands in script file that is encoded as either ASCII or UTF-8 text
set Set a settable parameter or show current settings of parameters
shell Execute a command as if at the OS prompt
shortcuts List available shortcuts
version Version command
When called with the ``-v`` flag for verbose help, the one-line description for
each command is provided by the first line of the docstring for that command's
associated ``do_*`` method.
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