examples/mrbgems: clarify the caller

Before this commit:

  mruby -e 'CRubyExtension.ruby_method' # => A Ruby Extension
  mruby -e 'CRubyExtension.c_method'    # => A C Extension
  mruby -e 'CExtension.c_method'        # => A C Extension
  mruby -e 'RubyExtension.ruby_method'  # => A Ruby Extension

After this commit:

  mruby -e 'CRubyExtension.ruby_method' # => CRubyExtension: A Ruby Extension
  mruby -e 'CRubyExtension.c_method'    # => CRubyExtension: A C Extension
  mruby -e 'CExtension.c_method'        # => CExtension: A C Extension
  mruby -e 'RubyExtension.ruby_method'  # => RubyExtension: A Ruby Extension

1 files changed, 1 insertions, 1 deletions

diff --git a/examples/mrbgems/ruby_extension_example/mrblib/example.rb b/examples/mrbgems/ruby_extension_example/mrblib/example.rb
index b07a2b580..b13aa002b 100644
--- a/examples/mrbgems/ruby_extension_example/mrblib/example.rb
+++ b/examples/mrbgems/ruby_extension_example/mrblib/example.rb
@@ -1,5 +1,5 @@
 class RubyExtension
   def RubyExtension.ruby_method
-    puts "A Ruby Extension"
+    puts "#{self}: A Ruby Extension"
   end
 end