lib/msgthr.rb in msgthr-1.1.0 vs lib/msgthr.rb in msgthr-1.2.0

@@ -146,11 +146,22 @@
   #   Mail or Tmail object for handling mail.
   #
   # If +mid+ is a String, it is recommended to freeze the string before
   # calling this method to avoid wasting memory on hash keys.  Likewise
   # is true for any String objects in +refs+.
-  def add(mid, refs, msg)
+  #
+  # Adding a message could link 2 messages in Msgthr,
+  # by making one message a child of the other.
+  # It's possible to have a callback called when a child is added
+  # by passing a block to this method.
+  # This block can access the child and parent messages. E.g.
+  #
+  #   msgthr.add(0, nil, '0')
+  #   msgthr.add(1, [0], '1') do |parent, child|
+  #     puts "#{parent.mid} -> #{child.mid}"
+  #   end
+  def add(mid, refs, msg) # :yields: parent, child
     @state == :init or raise StateError, "cannot add when already #@state"
 
     cur = @id_table[mid] ||= Msgthr::Container.new(mid)
     cur.msg = msg
     refs or return
@@ -164,15 +175,19 @@
 
       # link refs together in order implied,
       # but do not change existing links or loop
       if prev && !cont.parent && !cont.has_descendent(prev)
         prev.add_child(cont)
+        yield(prev, cont) if block_given?
       end
       prev = cont
     end
 
     # set parent of this message to be the last element in refs
-    prev.add_child(cur) if prev
+    if prev
+      prev.add_child(cur)
+      yield(prev, cur) if block_given?
+    end
   end
 end
 
 require_relative 'msgthr/container'