Python Dunder Method

In Python, built-in functions and operators work by inspecting objects for special behavior-defining methods. These methods are known as dunder methods because they are pref- and suffixed with two underscores.

---

__Abs__

---

__Add__

---

__AEnter__

See the specification for context managers.

---

__AExit__

See the specification for context managers.

---

__And__

---

__Bool__

---

__Ceil__

---

__Class__

---

__Copy__

See here for details.

---

__DeepCopy__

See here for details.

---

__Del__

---

__DelAttr__

---

__DelItem__

---

__Dir__

---

__DivMod__

---

__Doc__

---

__Enter__

See the specification for context managers.

---

__Eq__

---

__Exit__

See the specification for context managers.

---

__Float__

---

__Floor__

---

__FloorDiv__

---

__Format__

---

__Ge__

---

__GetAttr__

When attempting to access an object's attributes, conventionally an AttributeError will be raised if the lookup fails. To customize this behavior, a custom __getattr__() implementation can be set. This hooks into all attribute lookups that fail.

class Codes(object):
    def __getattr__(self, attr: str) -> str:
        return attr

---

__GetAttribute__

To override the attribute lookup process entirely for an object, a custom __getattribute__() implementation can be set.

class ObfuscatedData(object):
    def __getattribute__(self, attr: str) -> str:
        return 'REDACTED'

---

__GetItem__

---

__GetNewArgs__

---

__Gt__

---

__Hash__

---

__Index__

---

__Init__

---

__Init_Subclass__

---

__Int__

---

__Invert__

---

__Le__

---

__Len__

---

__LShift__

---

__Lt__

---

__Mod__

---

__Mul__

---

__Ne__

---

__Neg__

---

__New__

The __new__() method is called immediately when a class instance is created, even before __init__().

class Employee(object):
    def __new__(cls):
        print("INFO: creating new employee")
        return object.__new__(cls)

The return type is best annotated as typing.Self. See here for more details.

---

__Or__

---

__Pos__

---

__Pow__

---

__RAdd__

The reflected __add__() method.

---

__RAnd__

The reflected __and__() method.

---

__RDivMod__

The reflected __divmod__() method.

---

__Reduce__

---

__Reduce_Ex__

---

__Repr__

---

__RFloorDiv__

The reflected __floordiv__() method.

---

__RLShift__

The reflected __lshift__() method.

---

__RMod__

The reflected __mod__() method.

---

__RMul__

The reflected __mul__() method.

---

__ROr__

The reflected __or__() method.

---

__Round__

---

__RPow__

The reflected __pow__() method.

---

__RRShift__

The reflected __rshift__() method.

---

__RShift__

---

__RSub__

The reflected __sub__() method.

---

__RTrueDiv__

The reflected __truediv__() method.

---

__RXor__

The reflected __xor__() method.

---

__SetItem__

---

__SizeOf__

---

__Str__

---

__Sub__

---

__SubclassHook__

---

__TrueDiv__

---

__Trunc__

---

__Xor__

---

CategoryRicottone