add some methods to Symbol

mrbgems/mruby-symbol-ext/mrblib/symbol.rb

@@ -6,4 +6,55 @@ class Symbol
     end
   end
 
+  ##
+  # call-seq:
+  #   sym.length    -> integer
+  #
+  # Same as <code>sym.to_s.length</code>.
+
+  def length
+    self.to_s.length
+  end
+  alias :size :length
+
+  ##
+  # call-seq:
+  #   sym.capitalize  -> symbol
+  #
+  # Same as <code>sym.to_s.capitalize.intern</code>.
+
+  def capitalize
+    self.to_s.capitalize.intern
+  end
+
+  ##
+  # call-seq:
+  #   sym.downcase  -> symbol
+  #
+  # Same as <code>sym.to_s.downcase.intern</code>.
+
+  def downcase
+    self.to_s.downcase.intern
+  end
+
+  ##
+  # call-seq:
+  #   sym.upcase    -> symbol
+  #
+  # Same as <code>sym.to_s.upcase.intern</code>.
+
+  def upcase
+    self.to_s.upcase.intern
+  end
+
+  #
+  # call-seq:
+  #   sym.empty?   -> true or false
+  #
+  # Returns that _sym_ is :"" or not.
+
+  def empty?
+    self.to_s.empty?
+  end
+
 end

mrbgems/mruby-symbol-ext/test/symbol.rb

@@ -10,3 +10,25 @@ assert('Symbol.all_symbols') do
   symbols = Symbol.all_symbols.select{|sym|sym.to_s.include? '__symbol_test'}.sort
   assert_equal foo, symbols
 end
+
+assert("Symbol#length") do
+  assert_equal 5, :hello.size
+  assert_equal 5, :mruby.length
+end
+
+assert("Symbol#capitalize") do
+  assert_equal :Hello, :hello.capitalize
+  assert_equal :Hello, :HELLO.capitalize
+end
+
+assert("Symbol#downcase") do
+  assert_equal :hello, :hEllO.downcase
+end
+
+assert("Symbol#upcase") do
+  assert_equal :HELLO, :hEllO.upcase
+end
+
+assert("Symbol#empty?") do
+  assert_true :''.empty?
+end