Make messages returned by Thread objects owned

[notmuch] / bindings / python-cffi / notmuch2 / _message.py

diff --git a/bindings/python-cffi/notmuch2/_message.py b/bindings/python-cffi/notmuch2/_message.py
index c5fdbf6df94a635853d45daf18feec7b51550467..02de50adb68153b14825add4b2ba29d560215930 100644 (file)
--- a/bindings/python-cffi/notmuch2/_message.py
+++ b/bindings/python-cffi/notmuch2/_message.py
@@ -14,7 +14,7 @@ __all__ = ['Message']
 
 
 class Message(base.NotmuchObject):
-    """An email message stored in the notmuch database.
+    """An email message stored in the notmuch database retrieved via a query.
 
     This should not be directly created, instead it will be returned
     by calling methods on :class:`Database`.  A message keeps a
@@ -47,9 +47,7 @@ class Message(base.NotmuchObject):
     :type db: Database
     :param msg_p: The C pointer to the ``notmuch_message_t``.
     :type msg_p: <cdata>
-
     :param dup: Whether the message was a duplicate on insertion.
-
     :type dup: None or bool
     """
     _msg_p = base.MemoryPointer()
@@ -376,6 +374,26 @@ class Message(base.NotmuchObject):
             return self.messageid == other.messageid
 
 
+class OwnedMessage(Message):
+    """An email message owned by parent thread object.
+
+    This subclass of Message is used for messages that are retrieved
+    from the notmuch database via a parent :class:`notmuch2.Thread`
+    object, which "owns" this message.  This means that when this
+    message object is destroyed, by calling :func:`del` or
+    :meth:`_destroy` directly or indirectly, the message is not freed
+    in the notmuch API and the parent :class:`notmuch2.Thread` object
+    can return the same object again when needed.
+    """
+
+    @property
+    def alive(self):
+        return self._parent.alive
+
+    def _destroy(self):
+        pass
+
+
 class FilenamesIter(base.NotmuchIter):
     """Iterator for binary filenames objects."""
 
@@ -678,8 +696,9 @@ collections.abc.ValuesView.register(PropertiesValuesView)
 
 class MessageIter(base.NotmuchIter):
 
-    def __init__(self, parent, msgs_p, *, db):
+    def __init__(self, parent, msgs_p, *, db, msg_cls=Message):
         self._db = db
+        self._msg_cls = msg_cls
         super().__init__(parent, msgs_p,
                          fn_destroy=capi.lib.notmuch_messages_destroy,
                          fn_valid=capi.lib.notmuch_messages_valid,
@@ -688,4 +707,4 @@ class MessageIter(base.NotmuchIter):
 
     def __next__(self):
         msg_p = super().__next__()
-        return Message(self, msg_p, db=self._db)
+        return self._msg_cls(self, msg_p, db=self._db)