CodeQL documentation

__init__ method returns a value

ID: py/explicit-return-in-init
Kind: problem
Severity: error
Precision: very-high
Tags:
   - reliability
   - correctness
Query suites:
   - python-security-and-quality.qls

Click to see the query in the CodeQL repository

The __init__ method of a class is used to initialize new objects, not create them. As such, it should not return any value. Returning None is correct in the sense that no runtime error will occur, but it suggests that the returned value is meaningful, which it is not.

Recommendation

Convert the return expr statement to a plain return statement, or omit it altogether if it is at the end of the method.

Example

In this example, the __init__ method attempts to return the newly created object. This is an error and the return method should be removed.

class ExplicitReturnInInit(object):
    def __init__(self, i):
        self.i = i
        return self

References