Interfacing with notmuch

The notmuch module provides most of the functionality that a user is likely to need.


The underlying notmuch library is build on a hierarchical memory allocator called talloc. All objects derive from a top-level Database object.

This means that as soon as an object is deleted, all underlying derived objects such as Queries, Messages, Message, and Tags will be freed by the underlying library as well. Accessing these objects will then lead to segfaults and other unexpected behavior.

We implement reference counting, so that parent objects can be automatically freed when they are not needed anymore. For example:

db = Database('path',create=True)
msgs = Query(db,'from:myself').search_messages()

This returns Messages which internally contains a reference to its parent Query object. Otherwise the Query() would be immediately freed, taking our msgs down with it.

In this case, the above Query() object will be automatically freed whenever we delete all derived objects, ie in our case: del(msgs) would also delete the parent Query. It would not delete the parent Database() though, as that is still referenced from the variable db in which it is stored.

Pretty much the same is valid for all other objects in the hierarchy, such as Query, Messages, Message, and Tags.