lib/ruote/exp/fe_apply.rb in ruote-2.1.9 vs lib/ruote/exp/fe_apply.rb in ruote-2.1.10

@@ -53,15 +53,84 @@
   # All are equivalent to
   #
   #   echo 'nada'
   #
   #
+  # == apply and subprocesses
+  #
+  # There is an interesting way of using 'apply', it's close to the way of
+  # the Ruby "yield" expression.
+  #
+  #   pdef = Ruote.process_definition 'test' do
+  #     sequence do
+  #       handle do
+  #         participant 'alpha'
+  #       end
+  #       handle do
+  #         participant 'bravo'
+  #       end
+  #     end
+  #     define 'handle' do
+  #       sequence do
+  #         participant 'prepare_data'
+  #         apply
+  #         participant 'rearrange_data'
+  #       end
+  #     end
+  #   end
+  #
+  # With this process definition, the particpant alpha and bravo are handed
+  # a workitem in sequence, but each time, the data gets prepared and
+  # re-arranged.
+  #
+  # 'apply' simply picks the value of the tree to apply in the local variable
+  # 'tree'.
+  #
+  # Passing variables to applied trees is possible :
+  #
+  #   pdef = Ruote.process_definition do
+  #     handle do
+  #       participant '${v:target}', :message => 'x'
+  #     end
+  #     define 'handle' do
+  #       sequence do
+  #         participant 'prepare_data'
+  #         apply :v => 'alpha'
+  #         apply :v => 'bravo'
+  #         participant 'rearrange_data'
+  #       end
+  #     end
+  #   end
+  #
+  #
+  # == on_error
+  #
+  # It's OK, to place an on_error on the apply
+  #
+  #   pdef = Ruote.process_definition do
+  #     handle do
+  #       sequence do
+  #         echo 'in'
+  #         nemo
+  #       end
+  #     end
+  #     define 'handle' do
+  #       apply :on_error => 'notify' # <==
+  #       echo 'over.'
+  #     end
+  #     define 'notify' do
+  #       echo 'error'
+  #     end
+  #   end
+  #
   class ApplyExpression < FlowExpression
 
     names :apply
 
     # TODO : maybe accept directly ruby and xml (and json)
     # TODO : _yield ?
+
+    # TODO : apply [ 'echo', { 'nada' => nil }, [] ]
 
     def apply
 
       #
       # find 'tree'