__init__.py 文件源码

def get_cmdcls(self, cmdname, interface='ACTIVE', exclusive=False):
        """Resolve command name `cmdname` to command class

        If `interface` is 'ACTIVE', return command class from
        `active_commands`.

        If `interface` is 'ANY', return command class from `all_commands`.

        If `interface` is anything else, it must be an existing interface and
        only a command that supports it is returned.

        If `exclusive` evaluates to True, the returned command class does not
        support any other interfaces.

        Returns None if not matching command class is registered.
        """
        if interface == 'ACTIVE':
            cmdpool = self.active_commands
        elif interface == 'ANY':
            cmdpool = self.all_commands
        elif isinstance(interface, abc.Hashable):
            try:
                cmdpool = tuple(self._cmds[interface].values())
            except KeyError:
                raise ValueError('Unknown interface: {!r}'.format(interface))
        else:
            raise RuntimeError('Interface type must be hashable: {!r}'.format(interface))

        for cmd in cmdpool:
            if cmdname in cmd.names:
                if not exclusive:
                    return cmd
                elif cmd.provides == (interface,):
                    return cmd