Missing documentation for Custom Multi Commands

[omercnet]

When using Custom Multi Commands sphinx-click doesn't document the subcommands because multicommand.commands is empty

A quick solution on click's side would be to manually populate the commands attribute by loading all the commands but if you're trying to lazy load on purpose you may cry about performance issues.

class MyGroup(click.MultiCommand):
    """Dynamic group loader class."""

    folder = None

    def __init__(self, **kwargs):
        click.MultiCommand.__init__(self, **kwargs)
        self.commands = self._get_commands()

    def _get_commands(self):
        commands = {}
        for command in self.list_commands(self):
            commands[command] = self.get_command(self, command)

        return commands

I also patched a partial fix in omercnet@7497618 but it doesn't show the MultiCommand name in the docs (returns None), if anyone is willing to help finish it off that would be great :)

[omercnet]

The issue was that I didn't assign the name property to the custom command, opened #25