Make the argument of `Kernel#catch` optional as Ruby does

Also implement the following changes.

* Add tests
* Use `Object#equal?` to compare tags for Ruby compatibility
* Use `attr_reader`

1 files changed, 5 insertions, 10 deletions

diff --git a/mrbgems/mruby-catch/mrblib/catch.rb b/mrbgems/mruby-catch/mrblib/catch.rb
index f8dcb3e84..68b165c8d 100644
--- a/mrbgems/mruby-catch/mrblib/catch.rb
+++ b/mrbgems/mruby-catch/mrblib/catch.rb
@@ -1,22 +1,17 @@
 class ThrowCatchJump < Exception
+  attr_reader :_tag, :_val
   def initialize(tag, val)
-    @tag = tag
-    @val = val
+    @_tag = tag
+    @_val = val
     super("uncaught throw #{tag.inspect}")
   end
-  def _tag
-    @tag
-  end
-  def _val
-    @val
-  end
 end
 
 module Kernel
-  def catch(tag, &block)
+  def catch(tag=Object.new, &block)
     block.call(tag)
   rescue ThrowCatchJump => e
-    unless e._tag == tag
+    unless e._tag.equal?(tag)
       raise e
     end
     return e._val