4 files changed, 44 insertions, 0 deletions
diff --git a/build_config.rb b/build_config.rb
index c54c9d323..f697ec97d 100644
--- a/build_config.rb
+++ b/build_config.rb
@@ -26,6 +26,9 @@ MRuby::Build.new do |conf|
   # Use extensional String class
   conf.gem 'mrbgems/mruby-string-ext'
 
+  # Use extensional Numeric class
+  conf.gem 'mrbgems/mruby-numeric-ext'
+
   # Generate binaries
   # conf.bins = %w(mrbc mruby mirb)
   
diff --git a/mrbgems/mruby-numeric-ext/mrbgem.rake b/mrbgems/mruby-numeric-ext/mrbgem.rake
new file mode 100644
index 000000000..69c4fde4c
--- /dev/null
+++ b/mrbgems/mruby-numeric-ext/mrbgem.rake
@@ -0,0 +1,4 @@
+MRuby::Gem::Specification.new('mruby-numeric-ext') do |spec|
+  spec.license = 'MIT'
+  spec.authors = 'mruby developers'
+end
diff --git a/mrbgems/mruby-numeric-ext/src/numeric_ext.c b/mrbgems/mruby-numeric-ext/src/numeric_ext.c
new file mode 100644
index 000000000..b2c0e7986
--- /dev/null
+++ b/mrbgems/mruby-numeric-ext/src/numeric_ext.c
@@ -0,0 +1,30 @@
+#include "mruby.h"
+#include "mruby/numeric.h"
+
+static mrb_value
+mrb_int_chr(mrb_state *mrb, mrb_value x)
+{
+  mrb_int chr;
+  char c;
+
+  chr = mrb_fixnum(x);
+  if (chr >= (1 << CHAR_BIT)) {
+    mrb_raisef(mrb, E_RANGE_ERROR, "%ld out of char range", chr);
+  }
+  c = (char)chr;
+
+  return mrb_str_new(mrb, &c, 1);
+}
+
+void
+mrb_mruby_numeric_ext_gem_init(mrb_state* mrb)
+{
+  struct RClass *i = mrb_class_get(mrb, "Integer");
+
+  mrb_define_method(mrb, i, "chr",    mrb_int_chr,            ARGS_NONE());
+}
+
+void
+mrb_mruby_numeric_ext_gem_final(mrb_state* mrb)
+{
+}
diff --git a/mrbgems/mruby-numeric-ext/test/numeric.rb b/mrbgems/mruby-numeric-ext/test/numeric.rb
new file mode 100644
index 000000000..cafa0f1aa
--- /dev/null
+++ b/mrbgems/mruby-numeric-ext/test/numeric.rb
@@ -0,0 +1,7 @@
+##
+# Numeric(Ext) Test
+
+assert('Integer#chr') do
+  assert_equal(65.chr, "A")
+  assert_equal(0x42.chr, "B")
+end