enumatch

Strictly match all the possibilities of an enum

Use case

This little match function makes matching Python's enum fields safer by forcing us to match all the possibilities either explicitely or by using a default value.

Use ... (ellipsis) for default.

TIP: Create the matcher at compile-time to have zero runtime cost.

Example

from enum import Enum, auto
from enumatch import match

class Side(Enum):
    left = auto()
    right = auto()

# Define a simple matcher
matcher1 = match({Side.left: "Go left", Side.right: "Go right"})

assert matcher1[Side.left] == "Go left"
assert matcher1[Side.right] == "Go right"

# Define a matcher with a default case
matcher2 = match({Side.left: "Go left", ...: "Go right"})

assert matcher2[Side.left] == "Go left"
assert matcher2[Side.right] == "Go right"

# If all the possibilities are not handled, we get error
with pytest.raises(ValueError, match="missing possibilities: Side.right"):
    match({Side.left: "Go left"})