diff --git a/bin/box2.rb b/bin/box2.rb
new file mode 100755
index 0000000..d58b555
--- /dev/null
+++ b/bin/box2.rb
@@ -0,0 +1,19 @@
+#!/usr/bin/ruby
+
+require 'safebox'
+
+_ = _e = nil
+$stdout.print "(0)$ "
+db = {}
+db.taint
+STDIN.each.each_with_index do |line, i|
+	ret = Safebox.run line, Class.new( Safebox::Box), db, _, _e
+	if :value == ret.first
+		_ = ret.last
+		$stdout.puts "=> #{ret.last.inspect}"
+	else
+		_e = ret.last
+		$stdout.puts ret.last.inspect, ret.last.backtrace[0..-4].map( &"\t%s".method( :%)), "\tSafebox:1:in `run'"
+	end
+	$stdout.print "(#{i+1})$ "
+end
diff --git a/lib/safebox/box.rb b/lib/safebox/box.rb
index c85133f..1ac7ffa 100644
--- a/lib/safebox/box.rb
+++ b/lib/safebox/box.rb
@@ -3,7 +3,7 @@ require 'safebox/safebox'
 class Safebox::Box
 	attr_reader :_, :db
 
-	def initialize db, _ = nil, _e
+	def initialize db, _ = nil, _e = nil
 		@_, @db, @_e = _, db, _e
 	end
 
diff --git a/lib/safebox/safebox.rb b/lib/safebox/safebox.rb
index b6efb34..a848bdb 100644
--- a/lib/safebox/safebox.rb
+++ b/lib/safebox/safebox.rb
@@ -8,7 +8,7 @@ module Safebox
 				$SAFE = 4
 				this = box.new *paras
 				begin
-					[:value, this.instance_eval( exe, "Safebox")]
+					[:value, String === exe ? this.instance_eval( exe, "Safebox") : this.instance_eval( &exe)]
 				rescue Object
 					[:exception, $!]
 				end
@@ -23,5 +23,22 @@ module Safebox
 			end
 		end
 		alias new_class create_class
+
+		def on_exception exc
+			$stdout.puts "#{exc} (#{exc.class})\n\t#{exc.backtrace.join"\n\t"}"
+		rescue Object
+			on_exception $!
+		end
+
+		def eval *paras, &exe
+			ret = self.run( *paras, &exe)
+			case ret.first
+			when :exception  # Really unsecure. Somebody can create an own exception with own #to_s, #class or #backtrace.
+				on_exception ret.last
+				nil
+			when :value  then ret.last
+			end
+		end
+		public :eval
 	end
 end