Add documentation

Author: pitr-ch

lib/concurrent/obligation.rb

@@ -42,20 +42,30 @@ def incomplete?
       [:unscheduled, :pending].include? state
     end
 
+    # @returns [Object] see Dereferenceable#deref
     def value(timeout = nil)
       wait timeout
       deref
     end
 
+    # wait until Obligation is #complete?
+    # @param [Numeric] timeout the maximum time in second to wait.
+    # @return [Obligation] self
     def wait(timeout = nil)
       event.wait(timeout) if timeout != 0 && incomplete?
       self
     end
 
+    # wait until Obligation is #complete?
+    # @param [Numeric] timeout the maximum time in second to wait.
+    # @return [Obligation] self
+    # @raise [Exception] when #rejected? it raises #reason
     def no_error!(timeout = nil)
       wait(timeout).tap { raise self if rejected? }
     end
 
+    # @raise [Exception] when #rejected? it raises #reason
+    # @returns [Object] see Dereferenceable#deref
     def value!(timeout = nil)
       wait(timeout)
       if rejected?

lib/concurrent/observable.rb

@@ -10,6 +10,7 @@ def add_observer(*args, &block)
       observers.add_observer(*args, &block)
     end
 
+    # as #add_observer but it can be used for chaning
     # @return [Observable] self
     def with_observer(*args, &block)
       add_observer *args, &block