fix mypy errors, make lato compatibile with 3.9

.github/workflows/tests.yml

@@ -15,7 +15,7 @@ jobs:
     strategy:
       matrix:
         os: [Ubuntu, MacOS, Windows]
-        python-version: ["3.8", "3.9", "3.10", "3.11", "3.12"]
+        python-version: ["3.9", "3.10", "3.11", "3.12"]
         include:
           - os: Ubuntu
             python-version: pypy-3.8

lato/__init__.py

@@ -28,7 +28,7 @@
 
 def add_stderr_logger(
     level: int = logging.DEBUG,
-) -> logging.StreamHandler[typing.TextIO]:
+) -> logging.StreamHandler:
     """
     Helper for quickly adding a StreamHandler to the logger. Useful for
     debugging.

lato/application.py

@@ -1,7 +1,7 @@
 import logging
 from collections.abc import Callable
-from typing import Any
-
+from typing import Any, Optional, Union, List
+from lato.types import DependencyIdentifier
 from lato.application_module import ApplicationModule
 from lato.dependency_provider import BasicDependencyProvider, DependencyProvider
 from lato.message import Command, Event, Message
@@ -24,7 +24,7 @@ class Application(ApplicationModule):
     def __init__(
         self,
         name=__name__,
-        dependency_provider: DependencyProvider | None = None,
+        dependency_provider: Optional[DependencyProvider] = None,
         **kwargs,
     ):
         """Initialize the application instance.
@@ -42,10 +42,10 @@ def __init__(
         self._transaction_context_factory = None
         self._on_enter_transaction_context = lambda ctx: None
         self._on_exit_transaction_context = lambda ctx, exception=None: None
-        self._transaction_middlewares = []
-        self._composers: dict[str | Command, Callable] = {}
+        self._transaction_middlewares: List[Callable] = []
+        self._composers: dict[Union[Message, str], Callable] = {}
 
-    def get_dependency(self, identifier: str | type) -> Any:
+    def get_dependency(self, identifier: DependencyIdentifier) -> Any:
         """Gets a dependency from the dependency provider. Dependencies can be resolved either by name or by type.
 
         :param identifier: A string or a type representing the dependency.
@@ -54,10 +54,10 @@ def get_dependency(self, identifier: str | type) -> Any:
         """
         return self.dependency_provider.get_dependency(identifier)
 
-    def __getitem__(self, identifier: str | type) -> Any:
+    def __getitem__(self, identifier: DependencyIdentifier) -> Any:
         return self.get_dependency(identifier)
 
-    def call(self, func: Callable | str, *args, **kwargs):
+    def call(self, func: Union[Callable, str], *args, **kwargs):
         """Invokes a function with `args` and `kwargs` within the :class:`TransactionContext`.
         If `func` is a string, then it is an alias, and the corresponding handler for the alias is retrieved.
         Any missing arguments are provided by the dependency provider of a transaction context,

lato/application_module.py

@@ -1,8 +1,8 @@
 import logging
 from collections import defaultdict
 from collections.abc import Callable
-
 from lato.message import Message
+from lato.types import HandlerAlias
 from lato.utils import OrderedSet
 
 log = logging.getLogger(__name__)
@@ -28,7 +28,7 @@ def include_submodule(self, a_module: "ApplicationModule"):
         ), f"Can only include {ApplicationModule} instances, got {a_module}"
         self._submodules.add(a_module)
 
-    def handler(self, alias: type[Message] | str):
+    def handler(self, alias: HandlerAlias):
         """
         Decorator for registering a handler. Handler can be aliased by a name or by a message type.
 
@@ -65,12 +65,12 @@ def handler(self, alias: type[Message] | str):
         command handler called
 
         """
-        try:
-            is_message = issubclass(alias, Message)
-        except TypeError:
-            is_message = False
+        if isinstance(alias, type):
+            is_message_type = issubclass(alias, Message)
+        else:
+            is_message_type = False
 
-        if callable(alias) and not is_message:
+        if callable(alias) and not is_message_type:
             # decorator was called without any argument
             func = alias
             alias = func.__name__

lato/compositon.py

@@ -3,7 +3,7 @@
 from operator import add, or_
 from typing import Any, Optional
 
-from mergedeep import Strategy, merge
+from mergedeep import Strategy, merge  # type: ignore
 
 additive_merge = partial(merge, strategy=Strategy.TYPESAFE_ADDITIVE)
 

lato/dependency_provider.py

@@ -3,6 +3,7 @@
 from collections.abc import Callable
 from typing import Any
 
+from lato.types import DependencyIdentifier
 from lato.utils import OrderedDict
 
 
@@ -47,7 +48,7 @@ class DependencyProvider(ABC):
     allow_types = True
 
     @abstractmethod
-    def has_dependency(self, identifier: str | type) -> bool:
+    def has_dependency(self, identifier: DependencyIdentifier) -> bool:
         """
         Check if a dependency with the given identifier exists.
 
@@ -57,7 +58,7 @@ def has_dependency(self, identifier: str | type) -> bool:
         raise NotImplementedError()
 
     @abstractmethod
-    def register_dependency(self, identifier: str | type, dependency: Any):
+    def register_dependency(self, identifier: DependencyIdentifier, dependency: Any):
         """
         Register a dependency with a given identifier (name or type).
 
@@ -66,7 +67,7 @@ def register_dependency(self, identifier: str | type, dependency: Any):
         """
         raise NotImplementedError()
 
-    def get_dependency(self, identifier: str | type) -> Any:
+    def get_dependency(self, identifier: DependencyIdentifier) -> Any:
         """
         Retrieve a dependency using its identifier (name or type).
 
@@ -205,7 +206,7 @@ def __init__(self, *args, **kwargs):
         self._dependencies = {}
         self.update(*args, **kwargs)
 
-    def register_dependency(self, identifier: str | type, dependency: Any):
+    def register_dependency(self, identifier: DependencyIdentifier, dependency: Any):
         """
         Register a dependency with a given identifier (name or type).
 
@@ -217,7 +218,7 @@ def register_dependency(self, identifier: str | type, dependency: Any):
 
         self._dependencies[identifier] = dependency
 
-    def has_dependency(self, identifier: str | type) -> bool:
+    def has_dependency(self, identifier: DependencyIdentifier) -> bool:
         """
         Check if a dependency with the given identifier exists.
 
@@ -226,7 +227,7 @@ def has_dependency(self, identifier: str | type) -> bool:
         """
         return identifier in self._dependencies
 
-    def get_dependency(self, identifier: str | type) -> Any:
+    def get_dependency(self, identifier: DependencyIdentifier) -> Any:
         """
         Retrieve a dependency using its identifier (name or type).
 

lato/testing.py

@@ -1,36 +1,37 @@
 import contextlib
+from typing import Iterator
 
 from lato import Application
 
 
 @contextlib.contextmanager
-def override_app(application: Application, *args, **kwargs) -> Application:
+def override_app(application: Application, *args, **kwargs) -> Iterator[Application]:
     original_dependency_provider = application.dependency_provider
-    overriden_dependency_provider = original_dependency_provider.copy(*args, **kwargs)
+    overridden_dependency_provider = original_dependency_provider.copy(*args, **kwargs)
 
-    application.dependency_provider = overriden_dependency_provider
+    application.dependency_provider = overridden_dependency_provider
     yield application
 
     application.dependency_provider = original_dependency_provider
 
 
 @contextlib.contextmanager
-def override_ctx(application: Application, *args, **kwargs) -> Application:
+def override_ctx(application: Application, *args, **kwargs) -> Iterator[Application]:
     original_transaction_context = application.transaction_context
 
     def overriden_transaction_context(**dependencies):
         ctx = original_transaction_context(**dependencies)
         ctx.dependency_provider = ctx.dependency_provider.copy(*args, **kwargs)
         return ctx
 
-    application.transaction_context = overriden_transaction_context
+    application.transaction_context = overriden_transaction_context  # type: ignore
     yield application
 
-    application.transaction_context = original_transaction_context
+    application.transaction_context = original_transaction_context  # type: ignore
 
 
 @contextlib.contextmanager
-def override(application: Application, *args, **kwargs) -> Application:
+def override(application: Application, *args, **kwargs) -> Iterator[Application]:
     with override_app(application, **kwargs) as overridden1:
         with override_ctx(overridden1, **kwargs) as overridden2:
             yield overridden2

lato/transaction_context.py

@@ -2,8 +2,9 @@
 from collections import OrderedDict
 from collections.abc import Callable, Iterator
 from functools import partial
-from typing import Any, NewType, Optional
+from typing import Any, NewType, Optional, Union
 
+from lato.types import HandlerAlias
 from lato.compositon import compose
 from lato.dependency_provider import (
     BasicDependencyProvider,
@@ -12,7 +13,6 @@
 )
 from lato.message import Message
 
-Alias = NewType("Alias", Any)
 
 log = logging.getLogger(__name__)
 
@@ -38,7 +38,7 @@ class TransactionContext:
     dependency_provider_factory = BasicDependencyProvider
 
     def __init__(
-        self, dependency_provider: DependencyProvider | None = None, *args, **kwargs
+        self, dependency_provider: Optional[DependencyProvider] = None, *args, **kwargs
     ):
         """Initialize the transaction context instance.
 
@@ -56,8 +56,8 @@ def __init__(
         self._on_enter_transaction_context = lambda ctx: None
         self._on_exit_transaction_context = lambda ctx, exception=None: None
         self._middlewares: list[Callable] = []
-        self._composers: dict[str | Message, Callable] = {}
-        self._handlers_iterator: Iterator = lambda alias: iter([])
+        self._composers: dict[HandlerAlias, Callable] = {}
+        self._handlers_iterator: Callable[[HandlerAlias], Iterator[Callable]] = lambda alias: iter([])
 
     def configure(
         self,
@@ -96,7 +96,7 @@ def begin(self):
         """Should be used to start a transaction"""
         self._on_enter_transaction_context(self)
 
-    def end(self, exception: Exception = None):
+    def end(self, exception: Optional[Exception] = None):
         """Ends the transaction context by calling `on_exit_transaction_context` callback,
         optionally passing an exception.
 
@@ -163,26 +163,26 @@ def execute(self, message: Message) -> tuple[Any, ...]:
         composed_result = self._compose_results(message, values)
         return composed_result
 
-    def emit(self, message: str | Message, *args, **kwargs) -> dict[Callable, Any]:
+    def emit(self, message: Union[str, Message], *args, **kwargs) -> dict[Callable, Any]:
         # TODO: mark as obsolete
         return self.publish(message, *args, **kwargs)
 
-    def publish(self, message: str | Message, *args, **kwargs) -> dict[Callable, Any]:
+    def publish(self, message: Union[str, Message], *args, **kwargs) -> dict[Callable, Any]:
         """
         Publish a message by calling all handlers for that message.
 
-        :param message: The message object to publish, or a string.
+        :param message: The message object to publish, or an alias of a handler to call.
         :param args: Positional arguments to pass to the handlers.
         :param kwargs: Keyword arguments to pass to the handlers.
         :return: A dictionary mapping handlers to their results.
         """
-        alias = type(message) if isinstance(message, Message) else message
+        message_type = type(message) if isinstance(message, Message) else message
 
         if isinstance(message, Message):
             args = (message, *args)
 
         all_results = OrderedDict()
-        for handler in self._handlers_iterator(alias):
+        for handler in self._handlers_iterator(message_type):  # type: ignore
             self.set_dependency("message", message)
             # FIXME: push and pop current action instead of setting it
             self.current_handler = handler
@@ -214,4 +214,4 @@ def _compose_results(self, message: Message, results: tuple[Any, ...]) -> Any:
     @property
     def current_action(self) -> tuple[Message, Callable]:
         """Returns current message and handler being executed"""
-        return self.get_dependency("message"), self.current_handler
+        return self.get_dependency("message"), self.current_handler  # type: ignore

lato/types.py

@@ -0,0 +1,5 @@
+from typing import Union
+from lato.message import Message
+
+HandlerAlias = Union[type[Message], str]
+DependencyIdentifier = Union[type, str]

pyproject.toml

@@ -18,7 +18,7 @@ license = "MIT"
 "Bug Tracker" = "https://github.com/pgorecki/lato/issues"
 
 [tool.poetry.dependencies]
-python = "^3.8"
+python = "^3.9"
 pytest = "^7.4.2"
 pydantic = "^2.4.2"
 mergedeep = "^1.3.4"