lib.Distro: Add .id

Allow to query the distribution ID a Distro was instantiated with via
the .id property.

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

src/python/jw/pkg/lib/Distro.py

@@ -18,6 +18,10 @@ class Distro(abc.ABC):
     def __init__(self, ec: ExecContext):
         assert ec is not None
         self.__exec_context = ec
+        self.__id: str|None = None
+
+    def __set_id(self, id: str) -> None:
+        self.__id = id
 
     # == Load
 
@@ -38,10 +42,16 @@ class Distro(abc.ABC):
             log(ERR, f'Failed to import Distro module {module_path} ({str(e)})')
             raise
         cls = getattr(module, 'Distro')
-        return cls(*args, **kwargs)
+        ret = cls(*args, **kwargs)
+        ret.__set_id(backend_id)
+        return ret
 
     # == Convenience methods
 
+    @property
+    def id(self) -> str:
+        return self.__id
+
     @property
     def ctx(self) -> ExecContext:
         return self.__exec_context