I want to create a namedtuple
which represents the individual flags in a short bitfield. I'm trying to subclass it so that I can unpack the bitfield before the tuple is created. However, my current attempt isn't working:
class Status(collections.namedtuple("Status", "started checking start_after_check checked error paused queued loaded")):
__slots__ = ()
def __new__(cls, status):
super(cls).__new__(cls, status & 1, status & 2, status & 4, status & 8, status & 16, status & 32, status & 64, status & 128)
Now, my experience with super()
is limited and my experience with __new__
is virtually non-existent, so I'm not quite sure what to make of the (to me) enigmatic error TypeError: super.__new__(Status): Status is not a subtype of super
. Googling and digging into the docs haven't yielded anything enlightening.
Help?
You almost had it :-) There are just two little corrections:
The resulting code looks like this:
import collections
class Status(collections.namedtuple("Status", "started checking start_after_check checked error paused queued loaded")):
__slots__ = ()
def __new__(cls, status):
return super(cls, Status).__new__(cls, status & 1, status & 2, status & 4, status & 8, status & 16, status & 32, status & 64, status & 128)
It runs cleanly, just like you had expected:
>>> print Status(47)
Status(started=1, checking=2, start_after_check=4, checked=8, error=0, paused=32, queued=0, loaded=0)