jw.pkg.cmds.distro.Cmd: Add property util

Provide a property .util from Cmd, instanciated on demand from to the
respective distribution directory's Util class.

Signed-off-by: Jan Lindemann <jan@janware.com>

src/python/jw/pkg/cmds/distro/Cmd.py

@@ -4,12 +4,17 @@ import os, importlib
 
 from ..Cmd import Cmd as Base
 from ..CmdDistro import CmdDistro
+from .backend.Util import Util
 
 class Cmd(Base): # export
 
+    from .backend.Backend import Backend
+
     def __init__(self, parent: CmdDistro, name: str, help: str) -> None:
         super().__init__(parent, name, help)
-        self.__backend = None
+        self.__backend_path: str|None = None
+        self.__util: Util|None = None
+        self.__backend: Backend|None = None
 
     @property
     def distro_id(self) -> str:
@@ -20,9 +25,8 @@ class Cmd(Base): # export
         return self.parent.interactive
 
     @property
-    def _backend(self):
-        if self.__backend is None:
-            class_name = self.__class__.__name__[3:] # Get rid of "Cmd"
+    def _backend_path(self):
+        if self.__backend_path is None:
             backend_id = self.parent.distro_id.lower().replace('-', '_')
             match backend_id:
                 case 'ubuntu' | 'raspbian' | 'kali':
@@ -31,14 +35,28 @@ class Cmd(Base): # export
                     backend_id = 'redhat'
                 case 'opensuse_tumbleweed':
                     backend_id = 'suse'
-            module_name = (
+            self.__backend_path = (
                 os.path.splitext(__name__)[0]
                 + '.backend.'
                 + backend_id
                 + '.'
-                + class_name
             )
-            module = importlib.import_module(module_name)
-            cls = getattr(module, class_name)
-            self.__backend = cls(self)
+        return self.__backend_path
+
+    def _instantiate(self, name: str, *args, **kwargs):
+        module = importlib.import_module(self._backend_path + name)
+        cls = getattr(module, name)
+        return cls(self, *args, **kwargs)
+
+    @property
+    def util(self) -> Util:
+        if self.__util is None:
+            self.__util = self._instantiate('Util')
+        return self.__util
+
+    @property
+    def _backend(self) -> Backend:
+        if self.__backend is None:
+            name = self.__class__.__name__[3:] # Get rid of "Cmd"
+            self.__backend = self._instantiate(name)
         return self.__backend