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**********
Hacking BE
**********
Adding commands
===============
To write a plugin, you simply create a new file in the
``libbe/commands/`` directory. Take a look at one of the simpler
plugins (e.g. ``remove.py``) for an example of how that looks, and to
start getting a feel for the libbe interface.
See ``libbe/commands/base.py`` for the definition of the important
classes ``Option``, ``Argument``, ``Command``, ``InputOutput``,
``StorageCallbacks``, and ``UserInterface`` classes. You'll be
subclassing ``Command`` for your command, but all those classes will
be important.
Command completion
------------------
BE implements a general framework to make it easy to support command
completion for arbitrary plugins. In order to support this system,
any of your completable ``Argument()`` instances (in your command's
``.options`` or ``.args``) should be initialized with some valid
completion_callback function. Some common cases are defined in
``libbe.command.util``. If you need more flexibility, see
``libbe.command.list``'s ``--sort`` option for an example of
extensions via ``libbe.command.util.Completer``, or write a custom
completion function from scratch.
Adding user interfaces
======================
Take a look at ``libbe/ui/command_line.py`` for an example. Basically
you'll need to setup a ``UserInterface`` instance for running commands.
More details to come after I write an HTML UI...
Testing
=======
Run any tests in your module with::
be$ python test.py <python.module.name>
for example:
be$ python test.py libbe.command.merge
For a definition of "any tests", see ``test.py``'s
``add_module_tests()`` function.
Note that you will need to run ``make`` before testing a clean BE
branch to auto-generate required files like ``libbe/_version.py``.
Profiling
=========
Find out which 20 calls take the most cumulative time (time of
execution + childrens' times)::
$ python -m cProfile -o profile be [command] [args]
$ python -c "import pstats; p=pstats.Stats('profile'); p.sort_stats('cumulative').print_stats(20)"
It's often useful to toss::
import sys, traceback
print >> sys.stderr, '-'*60, '\n', '\n'.join(traceback.format_stack()[-10:])
into expensive functions (e.g. ``libbe.util.subproc.invoke()``) if
you're not sure why they're being called.
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