[Haml] Support non-String values for class attributes.

doc-src/HAML_CHANGELOG.md

@@ -55,12 +55,16 @@ When the {file:HAML_REFERENCE.md#ugly-option `:ugly` option} is enabled,
 {Haml::Helpers#haml_tag haml\_tag} and {Haml::Helpers#haml_concat haml\_concat}
 won't do any indentation of their arguments.
 
-### Object Reference Customization
+### Basic Tag Improvements
 
-It's now possible to customize the name used for {file:HAML_REFERENCE.md#object_reference_ object reference}
-for a given object by implementing the `haml_object_ref` method on that object.
-This method should return a string that will be used in place of the class name of the object
-in the generated class and id.
+* It's now possible to customize the name used for {file:HAML_REFERENCE.md#object_reference_ object reference}
+  for a given object by implementing the `haml_object_ref` method on that object.
+  This method should return a string that will be used in place of the class name of the object
+  in the generated class and id.
+
+* All attribute values may be non-String types.
+  Their `#to_s` method will be called to convert them to strings.
+  Previously, this only worked for attributes other than `class`.
 
 ### More Powerful `:autoclose` Option
 

lib/haml/buffer.rb

@@ -241,7 +241,7 @@ RUBY
     # Destructively modifies both `to` and `from`.
     #
     # @param to [{String => String}] The attribute hash to merge into
-    # @param from [{String => String}] The attribute hash to merge from
+    # @param from [{String => #to_s}] The attribute hash to merge from
     # @return [{String => String}] `to`, after being merged
     def self.merge_attrs(to, from)
       if to['id'] && from['id']
@@ -252,7 +252,7 @@ RUBY
 
       if to['class'] && from['class']
         # Make sure we don't duplicate class names
-        from['class'] = (from['class'].split(' ') | to['class'].split(' ')).sort.join(' ')
+        from['class'] = (from['class'].to_s.split(' ') | to['class'].split(' ')).sort.join(' ')
       elsif to['class'] || from['class']
         from['class'] ||= to['class']
       end

test/haml/engine_test.rb

@@ -141,6 +141,20 @@ HTML
 HAML
   end
 
+  def test_attributes_with_to_s
+    assert_equal(<<HTML, render(<<HAML))
+<p id='foo_2'></p>
+<p class='2 foo'></p>
+<p blaz='2'></p>
+<p 2='2'></p>
+HTML
+%p#foo{:id => 1+1}
+%p.foo{:class => 1+1}
+%p{:blaz => 1+1}
+%p{(1+1) => 1+1}
+HAML
+  end
+
   def test_nil_should_render_empty_tag
     assert_equal("<div class='no_attributes'></div>",
                  render(".no_attributes{:nil => nil}").chomp)