refactor: add Lifetime and Implementation types

Author: daireto

starlette_di/service_collection.py

@@ -2,12 +2,8 @@
 to register services.
 """
 
-from collections.abc import Callable
-from typing import Literal, TypeVar
-
 from .service_provider import Service, ServiceProvider
-
-T = TypeVar('T')
+from .types import Implementation, Lifetime, T
 
 
 class ServiceCollection:
@@ -49,7 +45,7 @@ def __init__(self) -> None:
     def add_singleton(
         self,
         service_type: type[T],
-        implementation: type[T] | Callable[..., T] | None = None,
+        implementation: Implementation = None,
     ):
         """Register a service as a singleton
         (one instance for the application lifetime).
@@ -61,7 +57,7 @@ def add_singleton(
         ----------
         service_type : type[T]
             Service type.
-        implementation : type[T] | Callable[..., T] | None, optional
+        implementation : Implementation, optional
             Implementation type or factory function, by default None.
 
         Returns
@@ -86,7 +82,7 @@ def add_singleton(
     def add_transient(
         self,
         service_type: type[T],
-        implementation: type[T] | Callable[..., T] | None = None,
+        implementation: Implementation = None,
     ):
         """Register a service as transient
         (new instance created each time it's requested).
@@ -98,7 +94,7 @@ def add_transient(
         ----------
         service_type : type[T]
             Service type.
-        implementation : type[T] | Callable[..., T] | None, optional
+        implementation : Implementation, optional
             Implementation type or factory function, by default None.
 
         Returns
@@ -123,7 +119,7 @@ def add_transient(
     def add_scoped(
         self,
         service_type: type[T],
-        implementation: type[T] | Callable[..., T] | None = None,
+        implementation: Implementation = None,
     ):
         """Register a service as scoped
         (one instance per request).
@@ -135,7 +131,7 @@ def add_scoped(
         ----------
         service_type : type[T]
             Service type.
-        implementation : type[T] | Callable[..., T] | None, optional
+        implementation : Implementation, optional
             Implementation type or factory function, by default None.
 
         Returns
@@ -159,9 +155,9 @@ def add_scoped(
 
     def add(
         self,
-        lifetime: Literal['singleton', 'scoped', 'transient'],
+        lifetime: Lifetime,
         service_type: type[T],
-        implementation: type[T] | Callable[..., T] | None = None,
+        implementation: Implementation = None,
     ):
         """Registers a service.
 
@@ -174,7 +170,7 @@ def add(
             Lifetime of the service.
         service_type : type[T]
             Service type.
-        implementation : type[T] | Callable[..., T] | None, optional
+        implementation : Implementation, optional
             Implementation type or factory function, by default None.
 
         Returns

starlette_di/service_provider.py

@@ -9,7 +9,9 @@ class to resolve services.
 from collections.abc import Callable
 from dataclasses import dataclass
 from inspect import Parameter, isclass, signature
-from typing import Any, Generic, Literal, TypeVar
+from typing import Any, Generic, TypeVar
+
+from .types import Implementation, Lifetime
 
 T = TypeVar('T', bound=object)
 
@@ -18,10 +20,10 @@ class to resolve services.
 class Service(Generic[T]):
     """Service information."""
 
-    lifetime: Literal['singleton', 'scoped', 'transient']
+    lifetime: Lifetime
     """Lifetime of the service."""
 
-    implementation: type[T] | Callable[..., T] | None
+    implementation: Implementation
     """Implementation of the service.
 
     It can be a class or a factory function.

starlette_di/types.py

@@ -1,11 +1,15 @@
 """This module provides the types used in the DI system."""
 
 from collections.abc import Awaitable, Callable
-from typing import ParamSpec, TypeVar
+from typing import Literal, ParamSpec, TypeVar
 
 from starlette.responses import Response
 
 T = TypeVar('T')
 P = ParamSpec('P')
 
 EndpointFunction = Callable[P, Awaitable[Response]]
+
+Implementation = type[T] | Callable[..., T] | None
+
+Lifetime = Literal['singleton', 'scoped', 'transient']