Tutorial: Extensions (Xontribs)¶
Take a deep breath and prepare for some serious Show & Tell; it’s time to learn about xonsh extensions!
Xonsh comes with some default set of extensions. These can be viewed here
.
Also checkout the list of Awesome Contributions from the community.
Overview¶
Xontributions, or xontribs
, are a set of tools and conventions for
extending the functionality of xonsh beyond what is provided by default. This
allows 3rd party developers and users to improve their xonsh experience without
having to go through the xonsh development and release cycle.
Many tools and libraries have extension capabilities. Here are some that we took inspiration from for xonsh:
Structure¶
Xontribs are modules written in either xonsh (*.xsh
) or Python (*.py
).
Normally, these are stored and found in an
implicit namespace package
called xontrib
. However, xontribs may be placed in any package or directory
that is on the $PYTHONPATH
.
If a module is in the xontrib
namespace package, it can be referred to just
by its module name. If a module is in any other package, then it must be
referred to by its full package path, separated by .
like you would in an
import statement. Of course, a module in xontrib
may be referred to
with the full xontrib.myext
. But just calling it myext
is a lot shorter
and one of the main advantages of placing an extension in the xontrib
namespace package.
Here is a sample file system layout and what the xontrib names would be:
|- xontrib/
|- javert.xsh # "javert", because in xontrib
|- your.py # "your",
|- eyes/
|- __init__.py
|- scream.xsh # "eyes.scream", because eyes is in xontrib
|- mypkg/
|- __init__.py # a regular package with an init file
|- other.py # not a xontrib
|- show.py # "mypkg.show", full module name
|- tell.xsh # "mypkg.tell", full module name
|- subpkg/
|- __init__.py
|- done.py # "mypkg.subpkg.done", full module name
You can also use cookiecutter with the xontrib template to easily create the layout for your xontrib package.
Loading Xontribs¶
Xontribs may be loaded in a few different ways: from the config file
(e.g. ~/.config/xonsh/rc.xsh
), dynamically at runtime with
the xontrib
command, or by importing the
module normally. Since these extensions are just Python modules, by
default, they cannot be unloaded (easily).
Note
When a xontrib is loaded its public variables are placed in the current
execution context unless __all__
is defined, just like in regular Python
modules.
Extensions are loaded via the xontrib
command, which is a xonsh default
alias. This command may be run from anywhere in a xonshrc file or at any point
after xonsh has started up. Loading is the default action of the xontrib
command. Thus the following methods for loading via this command are equivalent:
xontrib myext mpl mypkg.show
xontrib load myext mpl mypkg.show
Loading the same xontrib multiple times does not have any effect after the first. Xontribs are simply Python modules, and therefore follow the same caching rules. So by the same token, you can also import them normally. Of course, you have to use the full module name to import a xontrib:
import xontrib.mpl
from xontrib import myext
from mypkg.show import *
Listing Known Xontribs¶
In addition to loading extensions, the xontrib
command also allows you to
list the installed xontribs. This command will report if they are loaded
in the current session. To display this
information, pass the list
action to the xontrib
command:
>>> xontrib list
mpl not-loaded
myext not-loaded
For programmatic access, you may also have this command print a JSON formatted string:
>>> xontrib list --json mpl
{"mpl": {"loaded": false, "installed": true}}
Tell Us About Your Xontrib!¶
We request that you register your xontrib with us. We think that will make your contribution more discoverable.
To register a xontrib, create a PullRequest
at
Awesome-xontribs
repository. Also, if you use Github to host your code,
please add xonsh and xontrib
to the topics.
All of this let’s users know that your xontrib is out there, ready to be used. Of course, you’re under no obligation to register your xontrib. Users will still be able to load your xontrib, as long as they have it installed.
Go forth!