unidiomatic-typecheck / C0123

Message emitted:

Use isinstance() rather than type() for a typecheck.

Description:

The idiomatic way to perform an explicit typecheck in Python is to use isinstance(x, Y) rather than type(x) == Y, type(x) is Y. Though there are unusual situations where these give different results.

Problematic code:

test_score = {"Biology": 95, "History": 80}
if type(test_score) is dict:  # [unidiomatic-typecheck]
    pass

Correct code:

test_score = {"Biology": 95, "History": 80}
if isinstance(test_score, dict):
    pass

Related links:

• Builtin function type()

• Builtin function isinstance()

Created by the basic checker.