CODEWITHSUNDEEP
pythonbit-manipulationbitwise-operators
Jonathan Vanasco
Jonathan Vanasco

Reputation: 15680

python library for bitwise storage?

I need the need to be able to encode/decode some application 'constants' into a single variable.

the best description would be analogous to the octal notation in chmod , and would work something like this :

class Permissions(MagicalExistingClassSomewhere):
     EXECUTE = 1
     WRITE = 2
     READ = 4

a = Permissions(6)
print a
> [ Permissions.READ , Permissions.WRITE ]
a.add( Permissions.EXECUTE )
print a
> [ Permissions.READ , Permissions.WRITE , permissions.EXECUTE ]
print a.encode()
> 7
a.remove( Permissions.READ )
print a.encode()
> 3

has anyone seen a library that can abstract all the bitwise operations like this ? I've looked throughout PyPi and seen some libraries that focus on enum and bitwise, but nothing really does this sort of stuff.

Upvotes: 3

Views: 402

Answers (1)

will-hart
will-hart

Reputation: 3831

There is some discussion and some source code for this kind of thing at https://codereview.stackexchange.com/questions/23187/bitwise-flag-code-for-python

It allows you to set flags like:

# define your flags
class sec(FlagType):
  admin = 1
  read = 2
  write = 4
  usage = 8

flags = +sec.read -sec.write +sec.usage

flags.read
>>> True

Lots of feedback saying its not Pythonic though :)

Upvotes: 1

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