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WesR
WesR

Reputation: 1512

Interpret an integer as Python enum flags

I asked this question in interpret an integer as enum flags but did not state the challenge as clearly as I should have. I am looking for how to take a pure integer, not an instance of a class based on Flags, and interpret the integer according to the definitions in the class.

Suppose I have a Flag enum like this:

From enum import Flag
class suspicion(Flag):
     TOT_PCNT_LOW = 1
     IND_PCNT_LOW = 2
     IND_SCORE_LOW = 4

And suppose I have an integer that has bits set consistent with the definition, but is just an integer. It is ot an instance of the suspicion enumeration.

i == 3

How do I get a list of the names of the flags that correspond to the bits in the integer?

For example:

print(some_method(i))   # prints ["IND_PCNT_LOW", "TOT_PCNT_LOW"]

Upvotes: 3

Views: 1582

Answers (2)

Mahmoud
Mahmoud

Reputation: 11431

you can instantiate a new suspicion object with the value i. python will join corresponding names with a | symbol:

>>> i = 3

>>> suspicion(i)
<suspicion.TOT_PCNT_LOW|IND_PCNT_LOW: 3>

>>> suspicion(i).name
'TOT_PCNT_LOW|IND_PCNT_LOW'

>>> suspicion(i).name.split('|')
['TOT_PCNT_LOW', 'IND_PCNT_LOW']

Upvotes: 0

rdas
rdas

Reputation: 21275

You can iterate through the possible flags & evaluate if the corresponding bit is set. Use the enum value for the check. And then you can access the .name attribute of the enum object to get the name associated with the value

Like so:

from enum import Flag


class suspicion(Flag):
     TOT_PCNT_LOW = 1  # 001
     IND_PCNT_LOW = 2  # 010
     IND_SCORE_LOW = 4 # 100


i = 3 # 011


def flags_set(num):
    return [sus.name for sus in suspicion if num & sus.value]

print(flags_set(i))

Prints:

['TOT_PCNT_LOW', 'IND_PCNT_LOW']

Upvotes: 3

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