feat: ✨ Add message abstraction

Author: remimd

cq/__init__.py

@@ -1,16 +1,23 @@
-from ._core.command import (
+from ._core.dispatcher.bus import Bus
+from ._core.dispatcher.pipe import Pipe
+from ._core.dto import DTO
+from ._core.message import (
     AnyCommandBus,
     Command,
     CommandBus,
+    Event,
+    EventBus,
+    Message,
+    Query,
+    QueryBus,
     command_handler,
+    event_handler,
     find_command_bus,
+    find_event_bus,
+    find_query_bus,
+    query_handler,
 )
-from ._core.dispatcher.bus import Bus
-from ._core.dispatcher.pipe import Pipe
-from ._core.dto import DTO
-from ._core.event import Event, EventBus, event_handler, find_event_bus
 from ._core.middleware import Middleware, MiddlewareResult
-from ._core.query import Query, QueryBus, find_query_bus, query_handler
 
 __all__ = (
     "AnyCommandBus",
@@ -20,6 +27,7 @@
     "DTO",
     "Event",
     "EventBus",
+    "Message",
     "Middleware",
     "MiddlewareResult",
     "Pipe",

cq/_core/command.py

@@ -0,0 +1,51 @@
+from abc import ABC
+from typing import Any
+
+import injection
+
+from cq._core.dispatcher.bus import Bus, SimpleBus, SubscriberDecorator, TaskBus
+from cq._core.dto import DTO
+
+
+class Message(DTO, ABC):
+    __slots__ = ()
+
+
+class Command(Message, ABC):
+    __slots__ = ()
+
+
+class Event(Message, ABC):
+    __slots__ = ()
+
+
+class Query(Message, ABC):
+    __slots__ = ()
+
+
+type CommandBus[T] = Bus[Command, T]
+type EventBus = Bus[Event, None]
+type QueryBus[T] = Bus[Query, T]
+
+AnyCommandBus = CommandBus[Any]
+
+
+command_handler: SubscriberDecorator[Command, Any] = SubscriberDecorator(CommandBus)
+event_handler: SubscriberDecorator[Event, None] = SubscriberDecorator(EventBus)
+query_handler: SubscriberDecorator[Query, Any] = SubscriberDecorator(QueryBus)
+
+injection.set_constant(SimpleBus(), CommandBus, alias=True)
+injection.set_constant(TaskBus(), EventBus, alias=True)
+injection.set_constant(SimpleBus(), QueryBus, alias=True)
+
+
+def find_command_bus[T]() -> CommandBus[T]:
+    return injection.find_instance(CommandBus)
+
+
+def find_event_bus() -> EventBus:
+    return injection.find_instance(EventBus)
+
+
+def find_query_bus[T]() -> QueryBus[T]:
+    return injection.find_instance(QueryBus)