Data Model Reference Index¶

A comprehensive quick-reference catalog of Python's standard type hierarchy and special dunder method signatures.

Standard Type Hierarchy¶

Every entity in Python is an object. Each object possesses an identity (memory address, returned by id()), a type (returned by type()), and a value.

Object
 ├── None (type: NoneType)
 ├── NotImplemented (type: NotImplementedType)
 ├── Ellipsis (...) (type: ellipsis)
 ├── Numbers
 │    ├── Integral (int, bool)
 │    ├── Real (float)
 │    └── Complex (complex)
 ├── Sequences
 │    ├── Immutable (str, tuple, bytes)
 │    └── Mutable (list, bytearray)
 ├── Set Types
 │    ├── frozenset (Immutable)
 │    └── set (Mutable)
 ├── Mappings
 │    └── dict
 ├── Callable Types
 │    ├── User-defined functions
 │    ├── Built-in functions and methods
 │    ├── Generator functions
 │    ├── Coroutine functions
 │    └── Classes (calling invokes __new__ and __init__)
 └── Internal Types
      ├── Code objects
      ├── Frame objects
      ├── Traceback objects
      └── Slice objects

Complete Dunder Method Catalog¶

1. Object Lifecycle & Representation¶

Method	Invocation	Purpose
`__new__(cls, ...)`	`cls(...)`	Allocates new instance memory
`__init__(self, ...)`	`cls(...)`	Initializes instance attributes
`__del__(self)`	Garbage collection	Teardown before deallocation
`__repr__(self)`	`repr(obj)`	Unambiguous official string representation
`__str__(self)`	`str(obj)`, `print(obj)`	User-friendly readable string
`__format__(self, spec)`	`f"{obj:spec}"`	Custom formatting string spec
`__hash__(self)`	`hash(obj)`	Integer hash for set/dict membership
`__bool__(self)`	`bool(obj)`, `if obj:`	Truth value testing

2. Comparison Operations¶

Method	Operator	Meaning
`__lt__(self, other)`	`<`	Less than
`__le__(self, other)`	`<=`	Less than or equal
`__eq__(self, other)`	`==`	Equality
`__ne__(self, other)`	`!=`	Inequality
`__gt__(self, other)`	`>`	Greater than
`__ge__(self, other)`	`>=`	Greater than or equal

3. Attribute Access¶

Method	Invocation	Purpose
`__getattr__(self, name)`	`obj.name`	Fallback when attribute is NOT found
`__getattribute__(self, name)`	`obj.name`	Unconditional attribute lookup
`__setattr__(self, name, val)`	`obj.name = val`	Assigning instance attribute
`__delattr__(self, name)`	`del obj.name`	Deleting instance attribute
`__dir__(self)`	`dir(obj)`	List accessible attribute names

4. Container & Sequence Protocol¶

Method	Invocation	Purpose
`__len__(self)`	`len(obj)`	Element count
`__getitem__(self, key)`	`obj[key]`	Read item by key or slice
`__setitem__(self, key, val)`	`obj[key] = val`	Write item by key or slice
`__delitem__(self, key)`	`del obj[key]`	Delete item by key or slice
`__iter__(self)`	`iter(obj)`, `for x in obj:`	Return an iterator
`__next__(self)`	`next(iter)`	Advance iterator to next item
`__contains__(self, item)`	`item in obj`	Membership test
`__reversed__(self)`	`reversed(obj)`	Reverse iteration

5. Arithmetic & Bitwise Operations¶

Operation	Infix	Reflected (Right)	In-Place
Addition	`__add__(self, other)`	`__radd__`	`__iadd__`
Subtraction	`__sub__(self, other)`	`__rsub__`	`__isub__`
Multiplication	`__mul__(self, other)`	`__rmul__`	`__imul__`
Matrix Mul	`__matmul__(self, other)`	`__rmatmul__`	`__imatmul__`
True Division	`__truediv__(self, other)`	`__rtruediv__`	`__itruediv__`
Floor Division	`__floordiv__(self, other)`	`__rfloordiv__`	`__ifloordiv__`
Modulo	`__mod__(self, other)`	`__rmod__`	`__imod__`
Power	`__pow__(self, other)`	`__rpow__`	`__ipow__`
Bitwise AND	`__and__(self, other)`	`__rand__`	`__iand__`
Bitwise OR	`__or__(self, other)`	`__ror__`	`__ior__`
Bitwise XOR	`__xor__(self, other)`	`__rxor__`	`__ixor__`
Left Shift	`__lshift__(self, other)`	`__rlshift__`	`__ilshift__`
Right Shift	`__rshift__(self, other)`	`__rrshift__`	`__irshift__`

6. Context Managers¶

Method	Invocation	Purpose
`__enter__(self)`	`with obj:`	Enter context block
`__exit__(self, exc_type, exc_val, tb)`	`with obj:`	Exit context block & clean up
`__aenter__(self)`	`async with obj:`	Async enter context block
`__aexit__(self, exc_type, exc_val, tb)`	`async with obj:`	Async exit context block