Defines a generic class template for type-safe containers.

Declare a generic class to enable type-safe generic containers.

When you need to create a container class that should work with any type while retaining static type safety (e.g., a box, wrapper, or registry).

Inside a Python module where typing.Generic and TypeVar are imported, when defining data structures such as containers, wrappers, or registries.

class Container(Generic[T]):

class Container(Generic[T]):

[T]

• TypeVar
• Generic
• typing
• T
• TypeVar('T')

• Other type variable names like U
• V
• other class names like Box
• Wrapper
• Registry.

Forgetting to import TypeVar or Generic; forgetting to inherit from Generic; using a TypeVar without assigning it; using a concrete type as the type variable.

class Container: (non-generic); class Container(Generic[T, U]): (multiple type vars); class Container(Generic[T]) where T is bound to a base class.

Confusing Generic with inheritance from a base class; mixing up TypeVar assignment with concrete types; assuming Generic adds runtime behavior.

• Python generic class pattern
• TypeVar usage
• Generic container pattern

Indicates that the class is generic over type T, enabling static type checkers to infer element types when the class is parameterized.

Signals to type checkers (e.g., mypy) that Container can be parameterized with concrete types, allowing type-safe usage like Container[int] or Container[str].

Think of a generic box that can hold any type.

Advanced generic patterns: bounded type variables, multiple type variables, protocols, and generic protocols.