Fix errors on Ruby 1.8.7 where !~ and != can't be overridden, add…

… it to the README file

README.md

@@ -61,13 +61,12 @@ Here is a complete list of Arel method aliases:
 * For predicates:
   - `==`: `eq`
   - `=~`: `matches`
-  - `!~`: `does_not_match`
+  - `!~`: `does_not_match` (won't work in Ruby 1.8)
   - `>=`: `gteq`
   - `>` : `gt`
   - `<` : `lt`
   - `<=`: `lteq`
-  - `!=`: `not_eq`
-
+  - `!=`: `not_eq` (won't work in Ruby 1.8)
 
 * For combination
   - `&`: `and`

lib/sexy_scopes/arel/predicate_methods.rb

@@ -1,6 +1,13 @@
 module SexyScopes
   module Arel
     module PredicateMethods
+      class << self
+        private
+          def ruby_19_alias(new_name, old_name)
+            class_eval "alias #{new_name} #{old_name}" if RUBY_VERSION >= "1.9"
+          end
+      end
+
       def eq(other)
         extend_predicate(super)
       end
@@ -18,7 +25,7 @@ def matches(other)
       def does_not_match(other)
         extend_predicate(super)
       end
-      alias !~ does_not_match
+      ruby_19_alias '!~', 'does_not_match'
 
       def gteq(other)
         extend_predicate(super)
@@ -43,7 +50,7 @@ def lteq(other)
       def not_eq(other)
         extend_predicate(super)
       end
-      alias != not_eq
+      ruby_19_alias '!=', 'not_eq'
     end
   end
 end

spec/predicate_methods_spec.rb

@@ -5,6 +5,8 @@
     @attribute = User.attribute(:score)
   end
 
+  RUBY_19_METHODS = %w( != !~ )
+
   METHODS = {
     # Arel method   => [ Ruby operator, SQL operator ]
     :eq             => [ '==',  '= %s'        ],
@@ -28,9 +30,11 @@
 
       it { should convert_to_sql %{"users"."score" #{sql_operator % 42.0}} }
 
-      it "is aliased as `#{operator}`" do
-        @attribute.method(operator).should == @attribute.method(method)
-      end if operator
+      if operator && (!RUBY_19_METHODS.include?(operator) || ruby_19?)
+        it "is aliased as `#{operator}`" do
+          @attribute.method(operator).should == @attribute.method(method)
+        end
+      end
     end
   end
 end

spec/spec_helper.rb

@@ -10,7 +10,11 @@
 RSpec.configure do |config|
   config.extend Module.new {
     def ruby_19
-      yield if RUBY_VERSION >= "1.9"
+      yield if ruby_19?
+    end
+
+    def ruby_19?
+      RUBY_VERSION >= "1.9"
     end
   }
 end