Enhanced completion for Click
All the supported shells are able to complete all the command line arguments and options defined with click. In addition, fish and Zsh are also displaying the options and commands help during the completion.
In order to activate the completion, you need to:
- initialize the
- inform your shell that completion is available for your script, and how.
click in order to enhance the native
completion capabilities. This is done very simply:
import click_completion click_completion.init()
Once done, your click application is ready for completion.
Inform your shell
click_completion has some functions to produce the code to be executed
by the shell during the completion, and to permanently install this code
in a place that is automatically loaded by the shell.
The key functions are:
click-completion obviously depends on
Jinja2 is used to
generate the shell specific code.
And of course to make it useful, you'll need to use fish, Bash, Zsh or PowerShell.
click_complete has a
startswith function that can be replaced by a
custom one in order to customize the completion. Some extra environment
variable to be used during the completion can be passed to
install. An example is available in examples/click-completion-command.
Parameter type level
The custom parameter type may reimplement the
complete method in order
to customize the completion result. The
complete method takes the
current context and the incomplete argument to be completed. It can
return either a list of argument value that match the incomplete
argument, or a list of tuples
(arg, help). This last form is preferred
because it allows to display the help during the completion for the
shells that supports it.
An example can be found in the class
DocumentedChoice in click_completion/init.py.
How it works
As click, the general way
click_completion works is through a magic environment
<PROG_NAME> is your application
executable name in uppercase with dashes replaced by underscores.
If your tool is called foo-bar, then the magic variable is called
_FOO_BAR_COMPLETE. By exporting it with the
source value it will spit out the
activation script which can be trivially activated.
For instance, to enable fish completion for your foo-bar script, this is what
you would need to put into your
eval (env _FOO_BAR_COMPLETE=source-fish foo-bar)
From this point onwards, your script will have fish completion enabled.
The above activation example will always invoke your application on startup. This might be slowing down the shell activation time significantly if you have many applications. Alternatively, you could also ship a file with the contents of that, which is what Git and other systems are doing.
This can be easily accomplished:
_FOO_BAR_COMPLETE=source-fish foo-bar > ~/.config/fish/completions/foo-bar.fish
Licensed under the MIT, see LICENSE.
Contributions are all very welcome!
This may be in the form of bug reports, pull requests, …
A few subjects need some attention currently:
- argument parsing