Autoloading

Command Autoloading

ARC support dynamic loading of subcommands via the CLI#autoload method. For example:

# /home/user/timers.py
from arc import namespace

timers = namespace("timers")

@timers.subcommand()
def test():
    print("I've been autoloaded!")

# cli.py
from arc import CLI

cli = CLI()
cli.autoload("/home/users/timers.py")

cli()

Now we can run the timers:test command, without importing it directly

$ python cli.py timers:test
I've been autoladed!

CLI#autoload can accept an arbitrary number of paths to either files or directories. When given a file, it will do as above. When given a directory, it will attempt to load every file in that directory. In both cases, if no command is found, it will continue onto the next path rather than erroring.

Restrictions

Autoloaded Commands cannot overide commands installed by normal means. This is to prevent a user from accidentally overwriting a part of a tool they where unaware of with their own code.

The autoload method is available on the CLI object and not on the more general Command object. As such, commands can only be autoloaded onto the root CLI object and not into sub-commands. This is a style choice to prevent confusion / over-engineered complexity. However, while I don't reccomend this, if you still want to use autoloading with a sub-command, you can by using the internal Autoload object:

from arc import namespace
from arc.cli import Autoload

command = namespace("command")
Autoload(command, "/path/to/module").load()

Whatever commands are detected in /path/to/module will be installed on to the command object

Motivation

• Allows for consumers of a tool to extend to tool for their own use, without having to actually dig into the sourcecode
• It's neat :)