Update structure of subsystems manager

app-frame/macrostrat/app_frame/__init__.py

@@ -1,2 +1,4 @@
 from .core import Application
 from .compose import compose
+from .subsystems import SubsystemManager, Subsystem, SubsystemError
+from .exc import ApplicationError

app-frame/macrostrat/app_frame/subsystems/__init__.py

@@ -2,6 +2,7 @@
 from ..core import ApplicationBase
 from packaging.specifiers import InvalidSpecifier, SpecifierSet
 from packaging.version import Version
+from typing import Optional
 
 from macrostrat.utils.logs import get_logger
 
@@ -20,13 +21,18 @@ class SubsystemManager:
     """
 
     _hooks_fired = []
-    _app: ApplicationBase
+    _app: Optional[ApplicationBase] = None
+    _subsystem_cls: Subsystem = Subsystem
 
-    def __init__(self, app: ApplicationBase):
-        self._app = app
+    def __init__(self, subsystem_cls: Subsystem = Subsystem):
+        self._app = None
         self.__init_store = []
         self.__store = None
 
+        # Ensure that the plugin class is a subclass of Subsystem
+        assert issubclass(subsystem_cls, Subsystem) or subsystem_cls is Subsystem
+        self._subsystem_cls = subsystem_cls
+
     def __iter__(self):
         try:
             yield from self.__store

app-frame/macrostrat/app_frame/subsystems/defs.py

@@ -1,4 +1,4 @@
-from macrostrat.app_frame import ApplicationError
+from ..exc import ApplicationError
 
 
 class SubsystemError(ApplicationError):
@@ -17,7 +17,6 @@ class Subsystem:
 
     def __init__(self, app):
         self.app = app
-        self.db = self.app.db
 
-    def should_enable(self):
+    def should_enable(self, mgr: "SubsystemManager"):
         return True

app-frame/pyproject.toml

@@ -12,6 +12,7 @@ version = "1.2.0"
 "macrostrat.utils" = "^1.1.0"
 python = "^3.10"
 python-dotenv = "^1.0.0"
+toposort = "^1.5"
 rich = "^13"
 typer = "^0.9.0"