Completion for show-source/show-doc/?/$ Array#<tab>

lib/pry/command_set.rb

@@ -234,6 +234,12 @@ class Pry
         run action, *args
       end
 
+      c.class_eval do
+        define_method(:complete) do |input|
+          cmd.new(context).complete(input)
+        end
+      end
+
       c.group "Aliases"
 
       c

lib/pry/helpers/module_introspection_helpers.rb

@@ -127,6 +127,22 @@ class Pry
           retry
         end
       end
+
+      def complete(input)
+        if input =~ /([^ ]*)#([a-z0-9_]*)\z/
+          prefix, search = [$1, $2]
+          methods = begin
+                      Pry::Method.all_from_class(binding.eval(prefix))
+                    rescue RescuableException => e
+                      return super
+                    end
+          methods.map do |method|
+            [prefix, method.name].join('#') if method.name.start_with?(search)
+          end.compact
+        else
+          super
+        end
+      end
     end
   end
 end