Add support for Ruby 1.9.x.

lib/ar_mysql_column_charset.rb

@@ -1,5 +1,8 @@
 require 'active_record'
 
+# Module#prepend support for Ruby 1.9
+require 'prepend' unless Module.method_defined?(:prepend)
+
 module ActiveRecord::ConnectionAdapters
   class ColumnDefinition
     module CharsetSupport
@@ -77,4 +80,4 @@ module ActiveRecord::ConnectionAdapters
       prepend CharsetSupport
     end
   end
-end if Module.method_defined?(:prepend)  # ruby >=2.0
+end

lib/prepend.rb

@@ -0,0 +1,85 @@
+# Fake implementation of prepend(), which does not support overriding
+# inherited methods nor methods that are formerly overridden by
+# another invocation of prepend().
+#
+# Here's what <Original>.prepend(<Wrapper>) does:
+#
+# - Create an anonymous stub module (hereinafter <Stub>) and define
+#   <Stub>#<method> that calls #<method>_without_<Wrapper> for each
+#   instance method of <Wrapper>.
+#
+# - Rename <Original>#<method> to #<method>_without_<Wrapper> for each
+#   instance method of <Wrapper>.
+#
+# - Include <Stub> and <Wrapper> into <Original> in that order.
+#
+# This way, a call of <Original>#<method> is dispatched to
+# <Wrapper><method>, which may call super which is dispatched to
+# <Stub>#<method>, which finally calls
+# <Original>#<method>_without_<Wrapper> which is used to be called
+# <Original>#<method>.
+#
+# Usage:
+#
+#     class Mechanize
+#       # module with methods that overrides those of X
+#       module Y
+#       end
+#
+#       unless X.respond_to?(:prepend, true)
+#         require 'mechanize/prependable'
+#         X.extend(Prependable)
+#       end
+#
+#       class X
+#         prepend Y
+#       end
+#     end
+class Module
+  def prepend(mod)
+    stub = Module.new
+
+    mod_id = (mod.name || 'Module__%d' % mod.object_id).gsub(/::/, '__')
+
+    mod.instance_methods.each { |name|
+      method_defined?(name) or next
+
+      original = instance_method(name)
+      next if original.owner != self
+
+      name = name.to_s
+      name_without = name.sub(/(?=[?!=]?\z)/) { '_without_%s' % mod_id }
+
+      arity = original.arity
+      arglist = (
+        if arity >= 0
+          (1..arity).map { |i| 'x%d' % i }
+        else
+          (1..(-arity - 1)).map { |i| 'x%d' % i } << '*a'
+        end << '&b'
+      ).join(', ')
+
+      if name.end_with?('=')
+        stub.module_eval %{
+          def #{name}(#{arglist})
+            __send__(:#{name_without}, #{arglist})
+          end
+        }
+      else
+        stub.module_eval %{
+          def #{name}(#{arglist})
+            #{name_without}(#{arglist})
+          end
+        }
+      end
+      module_eval {
+        alias_method name_without, name
+        remove_method name
+      }
+    }
+
+    include stub
+    include mod
+  end
+  private :prepend
+end unless Module.method_defined?(:prepend)