#36962: Missing call to superclass `__init__` during object initialization
-------------------------+----------------------------------------
Reporter: kochrac | Type: Bug
Status: new | Component: Core (Other)
Version: 6.0 | Severity: Normal
Keywords: | Triage Stage: Unreviewed
Has patch: 1 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------+----------------------------------------
[https://github.com/django/django/blob/main/django/contrib/admin/widgets.py#L94-L626
/ L94-L626]
[https://github.com/django/django/blob/main/django/forms/widgets.py#L1116-L1116
/ L1116-L1116]
[https://github.com/django/django/blob/main/django/contrib/gis/forms/widgets.py#L12-L12
/ L12-L12]
[https://github.com/django/django/blob/main/django/db/models/expressions.py#L1880-L1880
/ L1880-L1880]
[https://github.com/django/django/blob/main/django/core/handlers/wsgi.py#L56-L56
/ L56-L56]
[https://github.com/django/django/blob/main/django/template/defaulttags.py#L909-L909
/ L909-L909]
[https://github.com/django/django/blob/main/django/contrib/admin/widgets.py#L630-L630
/ L630-L630]
[https://github.com/django/django/blob/main/django/contrib/gis/db/backends/oracle/adapter.py#L7-L7
/ L7-L7]
[https://github.com/django/django/blob/main/django/db/backends/ddl_references.py#L72-L72
/ L72-L72]
[https://github.com/django/django/blob/main/django/contrib/admin/widgets.py#L262-L262
/ L262-L262]
**Missing call to superclass __init__ during object initialization**
Pythonunlike some other object-oriented languages such as Java, allows the
developer complete freedom in when and how superclass initializers are
called during object initialization. However, the developer has
responsibility for ensuring that objects are properly initialized, and
that all superclass `__init__` methods are called.
If the `__init__` method of a superclass is not called during object
initialization, this can lead to errors due to the object not being fully
initialized, such as having missing attributes. A call to the `__init__`
method of a superclass during object initialization may be unintentionally
skipped:
- If a subclass calls the `__init__` method of the wrong class.
- If a call to the `__init__` method of one its base classes is omitted.
- If a call to `super().__init__` is used, but not all `__init__` methods
in the Method Resolution Order (MRO) chain themselves call `super()`. This
in particular arises more often in cases of multiple inheritance.
explicit calls to __init__ are used, but SportsCar erroneously calls
Vehicle.__init__. This is fixed in FixedSportsCar by calling Car.__init__.
{{{
class Vehicle(object):
def __init__(self):
self.mobile = True
class Car(Vehicle):
def __init__(self):
Vehicle.__init__(self)
self.car_init()
class SportsCar(Car, Vehicle):
def __init__(self):
Vehicle.__init__(self)
self.sports_car_init()
class FixedSportsCar(Car, Vehicle):
def __init__(self):
Car.__init__(self)
self.sports_car_init()
}}}
**References**
[https://docs.python.org/3/reference/datamodel.html#object.__init__ /
Python init]
[https://docs.python.org/3/reference/datamodel.html#object.__init__ /
Python Standard Library super]
[https://docs.python.org/3/glossary.html#term-method-resolution-order /
Python Glossary Method resolution order]
--
Ticket URL: <https://code.djangoproject.com/ticket/36962>
Django <https://code.djangoproject.com/>
The Web framework for perfectionists with deadlines.
--
You received this message because you are subscribed to the Google Groups
"Django updates" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to [email protected].
To view this discussion visit
https://groups.google.com/d/msgid/django-updates/0107019ca6a3f8db-5dcda568-f3cc-41fa-9b31-c592bd076611-000000%40eu-central-1.amazonses.com.
