[JimmXinu]

I've never done a template function before, so it's entirely possible I'm breaking rules for one or over-complicating it, but this is my version that can optionally return name or uuid for main, carda or cardb; defaulting to main and name.

Function: connected_device_info
Argument count: -1

Device Info for currently attached device.

May be passed 'main', 'carda', 'cardb' for info on a specific device location; default is 'main'.

May also (or instead) be passed 'name' or 'uuid' to get device location name or unique identifier; default is 'name'.

def evaluate(self, formatter, kwargs, mi, locals, *fnargs):
	from calibre.gui2.ui import get_gui
    dm = get_gui().device_manager
	info = dm.get_current_device_information()
	loc = 'main'
	val = 'device_name'
	for arg in fnargs:
		arg = arg.lower()
		if not arg:
			pass # ignore empty arg -- usually would be column.
		elif arg in ('main','carda','cardb','a','b'):
			loc = arg
			# for some reason, they are A and B in info, not carda and cardb.
			loc = loc.replace('card','') 	
			if loc in ('a','b'):
				loc = loc.upper()
		elif arg == 'name':	# default is already device_name. 
			pass
		elif arg == 'uuid':	# default is already device_name. 
			val = 'device_store_uuid'
		else:
			raise ValueError(
                         _('connected_device_info: invalid argument "{0}"'
                                    .format(arg)))
	if not info or not dm.is_device_present:
		return ''
	else:
		dev_info = info['info'][4]
		if loc in dev_info and val in dev_info[loc]:
			return dev_info[loc][val]
		else:
			return ''