lib/ably/realtime/presence.rb in ably-0.7.5 vs lib/ably/realtime/presence.rb in ably-0.7.6

@@ -263,17 +263,28 @@
       super
     end
 
     # Return the presence messages history for the channel
     #
+    # Once attached to a channel, you can retrieve presence message history on the channel before the
+    # channel was attached with the option <tt>until_attach: true</tt>.  This is very useful for
+    # developers who wish to capture new presence events as well as retrieve historical presence state with
+    # the guarantee that no presence history has been missed.
+    #
     # @param (see Ably::Rest::Presence#history)
     # @option options (see Ably::Rest::Presence#history)
+    # @option options [Boolean]  :until_attach  When true, request for history will be limited only to messages published before the associated channel was attached. The associated channel must be attached.
     #
-    # @yield [Ably::Models::PaginatedResource<Ably::Models::PresenceMessage>] An Array of {Ably::Models::PresenceMessage} objects that supports paging (#next_page, #first_page)
+    # @yield [Ably::Models::PaginatedResource<Ably::Models::PresenceMessage>] First {Ably::Models::PaginatedResource page} of {Ably::Models::PresenceMessage} objects accessible with {Ably::Models::PaginatedResource#items #items}.
     #
     # @return [Ably::Util::SafeDeferrable]
     #
     def history(options = {}, &callback)
+      if options.delete(:until_attach)
+        raise ArgumentError, 'option :until_attach cannot be specified if the channel is not attached' unless channel.attached?
+        options[:from_serial] = channel.attached_serial
+      end
+
       async_wrap(callback) do
         rest_presence.history(options.merge(async_blocking_operations: true))
       end
     end