A virtual folder representing a saved search.
VeeFolder is a Folder subclass that implements virtual folders. A virtual folder is like a persistent search over one or more real folders: it automatically stays up to date as messages arrive or change, and otherwise behaves like a normal folder to client code.
The set of source folders is managed with add_folder_sync,
remove_folder_sync, and
set_folders_sync. The search expression (a CamelFolderSearch
s-expression) is set with set_expression_sync.
Virtual folder UIDs are composed of an 8-character hash of the physical folder plus the original UID, making them stable across renames and allowing efficient reverse-lookup via get_location.
Virtual folders are normally parented to a VeeStore. The special UNMATCHED folder represents all messages in the tracked folders that are not matched by any other virtual folder.