Move #as to AliasPredication, stop overriding Function's #as.

lib/arel.rb

@@ -4,6 +4,7 @@
 require 'arel/expressions'
 require 'arel/predications'
 require 'arel/math'
+require 'arel/alias_predication'
 require 'arel/order_predications'
 require 'arel/table'
 require 'arel/attributes'

lib/arel/alias_predication.rb

+module Arel
+  module AliasPredication
+    def as other
+      Nodes::As.new self, Nodes::SqlLiteral.new(other.to_s)
+    end
+  end
+end
\ No newline at end of file

lib/arel/attributes/attribute.rb

@@ -3,6 +3,7 @@ module Attributes
     class Attribute < Struct.new :relation, :name
       include Arel::Expressions
       include Arel::Predications
+      include Arel::AliasPredication
       include Arel::OrderPredications
       include Arel::Math
 

lib/arel/nodes/function.rb

@@ -6,12 +6,12 @@ class Function < Arel::Nodes::Node
 
       def initialize expr, aliaz = nil
         @expressions = expr
-        @alias       = aliaz
+        @alias       = aliaz && SqlLiteral.new(aliaz.to_s)
         @distinct    = false
       end
 
       def as aliaz
-        self.alias = SqlLiteral.new(aliaz)
+        self.alias = SqlLiteral.new(aliaz.to_s)
         self
       end
     end

lib/arel/nodes/infix_operation.rb

@@ -4,6 +4,7 @@ module Nodes
     class InfixOperation < Binary
       include Arel::Expressions
       include Arel::Predications
+      include Arel::AliasPredication
       include Arel::Math
 
       attr_reader :operator

lib/arel/nodes/sql_literal.rb

@@ -3,6 +3,7 @@ module Nodes
     class SqlLiteral < String
       include Arel::Expressions
       include Arel::Predications
+      include Arel::AliasPredication
       include Arel::OrderPredications
     end
   end

lib/arel/predications.rb

 module Arel
   module Predications
 
-    def as other
-      Nodes::As.new self, Nodes::SqlLiteral.new(other)
-    end
-
     def not_eq other
       Nodes::NotEqual.new self, other
     end

test/nodes/test_named_function.rb

@@ -8,6 +8,23 @@ def test_construct
         assert_equal 'omg', function.name
         assert_equal 'zomg', function.expressions
       end
+
+      def test_function_alias
+        function = NamedFunction.new 'omg', 'zomg'
+        function = function.as('wth')
+        assert_equal 'omg', function.name
+        assert_equal 'zomg', function.expressions
+        assert_kind_of SqlLiteral, function.alias
+        assert_equal 'wth', function.alias
+      end
+
+      def test_construct_with_alias
+        function = NamedFunction.new 'omg', 'zomg', 'wth'
+        assert_equal 'omg', function.name
+        assert_equal 'zomg', function.expressions
+        assert_kind_of SqlLiteral, function.alias
+        assert_equal 'wth', function.alias
+      end
     end
   end
 end

test/visitors/test_depth_first.rb

@@ -52,14 +52,14 @@ def test_raises_with_object
         define_method("test_#{klass.name.gsub('::', '_')}") do
           func = klass.new(:a, :b)
           @visitor.accept func
-          assert_equal [:a, :b, false, func], @collector.calls
+          assert_equal [:a, "b", false, func], @collector.calls
         end
       end
 
       def test_named_function
         func = Arel::Nodes::NamedFunction.new(:a, :b, :c)
         @visitor.accept func
-        assert_equal [:a, :b, false, :c, func], @collector.calls
+        assert_equal [:a, :b, false, "c", func], @collector.calls
       end
 
       def test_lock
@@ -71,7 +71,7 @@ def test_lock
       def test_count
         count = Nodes::Count.new :a, :b, :c
         @visitor.accept count
-        assert_equal [:a, :c, :b, count], @collector.calls
+        assert_equal [:a, "c", :b, count], @collector.calls
       end
 
       def test_inner_join