add type hint for >3.9

patterns/behavioral/chain_of_responsibility.py

@@ -19,11 +19,10 @@
 """
 
 from abc import ABC, abstractmethod
-from typing import Optional, Tuple
 
 
 class Handler(ABC):
-    def __init__(self, successor: Optional["Handler"] = None):
+    def __init__(self, successor: "Handler | None" = None):
         self.successor = successor
 
     def handle(self, request: int) -> None:
@@ -39,7 +38,7 @@ def handle(self, request: int) -> None:
             self.successor.handle(request)
 
     @abstractmethod
-    def check_range(self, request: int) -> Optional[bool]:
+    def check_range(self, request: int) -> bool | None:
         """Compare passed value to predefined interval"""
 
 
@@ -49,7 +48,7 @@ class ConcreteHandler0(Handler):
     """
 
     @staticmethod
-    def check_range(request: int) -> Optional[bool]:
+    def check_range(request: int) -> bool | None:
         if 0 <= request < 10:
             print(f"request {request} handled in handler 0")
             return True
@@ -61,7 +60,7 @@ class ConcreteHandler1(Handler):
 
     start, end = 10, 20
 
-    def check_range(self, request: int) -> Optional[bool]:
+    def check_range(self, request: int) -> bool | None:
         if self.start <= request < self.end:
             print(f"request {request} handled in handler 1")
             return True
@@ -71,21 +70,21 @@ def check_range(self, request: int) -> Optional[bool]:
 class ConcreteHandler2(Handler):
     """... With helper methods."""
 
-    def check_range(self, request: int) -> Optional[bool]:
+    def check_range(self, request: int) -> bool | None:
         start, end = self.get_interval_from_db()
         if start <= request < end:
             print(f"request {request} handled in handler 2")
             return True
         return None
 
     @staticmethod
-    def get_interval_from_db() -> Tuple[int, int]:
+    def get_interval_from_db() -> tuple[int, int]:
         return (20, 30)
 
 
 class FallbackHandler(Handler):
     @staticmethod
-    def check_range(request: int) -> Optional[bool]:
+    def check_range(request: int) -> bool | None:
         print(f"end of chain, no handler for {request}")
         return False
 

patterns/behavioral/command.py

@@ -20,7 +20,6 @@
 https://docs.djangoproject.com/en/2.1/ref/request-response/#httprequest-objects
 """
 
-from typing import List, Union
 
 
 class HideFileCommand:
@@ -30,7 +29,7 @@ class HideFileCommand:
 
     def __init__(self) -> None:
         # an array of files hidden, to undo them as needed
-        self._hidden_files: List[str] = []
+        self._hidden_files: list[str] = []
 
     def execute(self, filename: str) -> None:
         print(f"hiding {filename}")
@@ -48,7 +47,7 @@ class DeleteFileCommand:
 
     def __init__(self) -> None:
         # an array of deleted files, to undo them as needed
-        self._deleted_files: List[str] = []
+        self._deleted_files: list[str] = []
 
     def execute(self, filename: str) -> None:
         print(f"deleting {filename}")
@@ -64,7 +63,7 @@ class MenuItem:
     The invoker class. Here it is items in a menu.
     """
 
-    def __init__(self, command: Union[HideFileCommand, DeleteFileCommand]) -> None:
+    def __init__(self, command: HideFileCommand | DeleteFileCommand) -> None:
         self._command = command
 
     def on_do_press(self, filename: str) -> None:

patterns/behavioral/memento.py

@@ -6,7 +6,7 @@
 """
 
 from copy import copy, deepcopy
-from typing import Callable, List
+from typing import Callable
 
 
 def memento(obj: Any, deep: bool = False) -> Callable:
@@ -26,7 +26,7 @@ class Transaction:
     """
 
     deep = False
-    states: List[Callable[[], None]] = []
+    states: list[Callable[[], None]] = []
 
     def __init__(self, deep: bool, *targets: Any) -> None:
         self.deep = deep

patterns/behavioral/observer.py

@@ -12,7 +12,6 @@
 # observer.py
 
 from __future__ import annotations
-from typing import List
 
 class Observer:
     def update(self, subject: Subject) -> None:
@@ -26,7 +25,7 @@ def update(self, subject: Subject) -> None:
 
 
 class Subject:
-    _observers: List[Observer]
+    _observers: list[Observer]
 
     def __init__(self) -> None:
         """

patterns/behavioral/registry.py

@@ -1,8 +1,5 @@
-from typing import Dict
-
-
 class RegistryHolder(type):
-    REGISTRY: Dict[str, "RegistryHolder"] = {}
+    REGISTRY: dict[str, "RegistryHolder"] = {}
 
     def __new__(cls, name, bases, attrs):
         new_cls = type.__new__(cls, name, bases, attrs)

patterns/behavioral/specification.py

@@ -6,7 +6,6 @@
 """
 
 from abc import abstractmethod
-from typing import Union
 
 
 class Specification:
@@ -44,7 +43,7 @@ def __init__(self, one: "Specification", other: "Specification") -> None:
         self._one: Specification = one
         self._other: Specification = other
 
-    def is_satisfied_by(self, candidate: Union["User", str]) -> bool:
+    def is_satisfied_by(self, candidate: "User" | str) -> bool:
         return bool(
             self._one.is_satisfied_by(candidate)
             and self._other.is_satisfied_by(candidate)
@@ -56,7 +55,7 @@ def __init__(self, one: "Specification", other: "Specification") -> None:
         self._one: Specification = one
         self._other: Specification = other
 
-    def is_satisfied_by(self, candidate: Union["User", str]):
+    def is_satisfied_by(self, candidate: "User" | str):
         return bool(
             self._one.is_satisfied_by(candidate)
             or self._other.is_satisfied_by(candidate)
@@ -67,7 +66,7 @@ class NotSpecification(CompositeSpecification):
     def __init__(self, wrapped: "Specification"):
         self._wrapped: Specification = wrapped
 
-    def is_satisfied_by(self, candidate: Union["User", str]):
+    def is_satisfied_by(self, candidate: "User" | str):
         return bool(not self._wrapped.is_satisfied_by(candidate))
 
 
@@ -77,7 +76,7 @@ def __init__(self, super_user: bool = False) -> None:
 
 
 class UserSpecification(CompositeSpecification):
-    def is_satisfied_by(self, candidate: Union["User", str]) -> bool:
+    def is_satisfied_by(self, candidate: "User" | str) -> bool:
         return isinstance(candidate, User)
 
 

patterns/behavioral/strategy.py

@@ -29,7 +29,7 @@ def validate(obj: Order, value: Callable) -> bool:
     def __set_name__(self, owner, name: str) -> None:
         self.private_name = f"_{name}"
 
-    def __set__(self, obj: Order, value: Callable = None) -> None:
+    def __set__(self, obj: Order, value: Callable | None = None) -> None:
         if value and self.validate(obj, value):
             setattr(obj, self.private_name, value)
         else:
@@ -42,7 +42,7 @@ def __get__(self, obj: object, objtype: type = None):
 class Order:
     discount_strategy = DiscountStrategyValidator()
 
-    def __init__(self, price: float, discount_strategy: Callable = None) -> None:
+    def __init__(self, price: float, discount_strategy: Callable | None = None) -> None:
         self.price: float = price
         self.discount_strategy = discount_strategy
 

patterns/behavioral/visitor.py

@@ -14,7 +14,6 @@
 which is then being used e.g. in tools like `pyflakes`.
 - `Black` formatter tool implements it's own: https://github.com/ambv/black/blob/master/black.py#L718
 """
-from typing import Union
 
 
 class Node:
@@ -34,7 +33,7 @@ class C(A, B):
 
 
 class Visitor:
-    def visit(self, node: Union[A, C, B], *args, **kwargs) -> None:
+    def visit(self, node: A | C | B, *args, **kwargs) -> None:
         meth = None
         for cls in node.__class__.__mro__:
             meth_name = "visit_" + cls.__name__
@@ -49,7 +48,7 @@ def visit(self, node: Union[A, C, B], *args, **kwargs) -> None:
     def generic_visit(self, node: A, *args, **kwargs) -> None:
         print("generic_visit " + node.__class__.__name__)
 
-    def visit_B(self, node: Union[C, B], *args, **kwargs) -> None:
+    def visit_B(self, node: C | B, *args, **kwargs) -> None:
         print("visit_B " + node.__class__.__name__)
 
 

patterns/creational/abstract_factory.py

@@ -31,7 +31,6 @@
 """
 
 import random
-from typing import Type
 
 
 class Pet:
@@ -64,7 +63,7 @@ def __str__(self) -> str:
 class PetShop:
     """A pet shop"""
 
-    def __init__(self, animal_factory: Type[Pet]) -> None:
+    def __init__(self, animal_factory: type[Pet]) -> None:
         """pet_factory is our abstract factory.  We can set it at will."""
 
         self.pet_factory = animal_factory
@@ -91,7 +90,7 @@ def main() -> None:
 
 if __name__ == "__main__":
     animals = [Dog, Cat]
-    random_animal: Type[Pet] = random.choice(animals)
+    random_animal: type[Pet] = random.choice(animals)
 
     shop = PetShop(random_animal)
     import doctest

patterns/creational/borg.py

@@ -33,11 +33,8 @@
 Provides singleton-like behavior sharing state between instances.
 """
 
-from typing import Dict
-
-
 class Borg:
-    _shared_state: Dict[str, str] = {}
+    _shared_state: dict[str, str] = {}
 
     def __init__(self) -> None:
         self.__dict__ = self._shared_state

patterns/creational/factory.py

@@ -22,7 +22,7 @@
 Creates objects without having to specify the exact class.
 """
 
-from typing import Dict, Protocol, Type
+from typing import Protocol
 
 
 class Localizer(Protocol):
@@ -49,7 +49,7 @@ def localize(self, msg: str) -> str:
 
 def get_localizer(language: str = "English") -> Localizer:
     """Factory"""
-    localizers: Dict[str, Type[Localizer]] = {
+    localizers: dict[str, type[Localizer]] = {
         "English": EnglishLocalizer,
         "Greek": GreekLocalizer,
     }

patterns/creational/lazy_evaluation.py

@@ -20,15 +20,15 @@
 """
 
 import functools
-from typing import Callable, Type
+from typing import Callable
 
 
 class lazy_property:
     def __init__(self, function: Callable) -> None:
         self.function = function
         functools.update_wrapper(self, function)
 
-    def __get__(self, obj: "Person", type_: Type["Person"]) -> str:
+    def __get__(self, obj: "Person", type_: type["Person"]) -> str:
         if obj is None:
             return self
         val = self.function(obj)

patterns/creational/pool.py

@@ -29,7 +29,6 @@
 """
 from queue import Queue
 from types import TracebackType
-from typing import Union
 
 
 class ObjectPool:
@@ -44,9 +43,9 @@ def __enter__(self) -> str:
 
     def __exit__(
         self,
-        Type: Union[type[BaseException], None],
-        value: Union[BaseException, None],
-        traceback: Union[TracebackType, None],
+        Type: type[BaseException] | None,
+        value: BaseException | None,
+        traceback: TracebackType | None,
     ) -> None:
         if self.item is not None:
             self._queue.put(self.item)

patterns/fundamental/delegation_pattern.py

@@ -33,7 +33,7 @@ class Delegator:
     def __init__(self, delegate: Delegate) -> None:
         self.delegate = delegate
 
-    def __getattr__(self, name: str) -> Any | Callable:
+    def __getattr__(self, name: str) -> Any:
         attr = getattr(self.delegate, name)
 
         if not callable(attr):

patterns/other/graph_search.py

@@ -1,4 +1,4 @@
-from typing import Any, Dict, List, Optional, Union
+from typing import Any
 
 
 class GraphSearch:
@@ -8,12 +8,12 @@ class GraphSearch:
     dfs stands for Depth First Search
     bfs stands for Breadth First Search"""
 
-    def __init__(self, graph: Dict[str, List[str]]) -> None:
+    def __init__(self, graph: dict[str, list[str]]) -> None:
         self.graph = graph
 
     def find_path_dfs(
-        self, start: str, end: str, path: Optional[List[str]] = None
-    ) -> Optional[List[str]]:
+        self, start: str, end: str, path: list[str] | None = None
+    ) -> list[str] | None:
         path = path or []
 
         path.append(start)
@@ -26,8 +26,8 @@ def find_path_dfs(
                     return newpath
 
     def find_all_paths_dfs(
-        self, start: str, end: str, path: Optional[List[str]] = None
-    ) -> List[Union[List[str], Any]]:
+        self, start: str, end: str, path: list[str] | None = None
+    ) -> list[list[str] | Any]:
         path = path or []
         path.append(start)
         if start == end:
@@ -40,8 +40,8 @@ def find_all_paths_dfs(
         return paths
 
     def find_shortest_path_dfs(
-        self, start: str, end: str, path: Optional[List[str]] = None
-    ) -> Optional[List[str]]:
+        self, start: str, end: str, path: list[str] | None = None
+    ) -> list[str] | None:
         path = path or []
         path.append(start)
 
@@ -56,7 +56,7 @@ def find_shortest_path_dfs(
                         shortest = newpath
         return shortest
 
-    def find_shortest_path_bfs(self, start: str, end: str) -> Optional[List[str]]:
+    def find_shortest_path_bfs(self, start: str, end: str) -> list[str] | None:
         """
         Finds the shortest path between two nodes in a graph using breadth-first search.