Methods for adding attributes to elements.

The methods XML::Element#add_attribute and XML::Element#set can be used to more
easily add attributes to elements. The first method simply adds an Attribute
instance and links it to the element. This allows for fine grained control over
what data the attribute should contain. The second method ("set") simply sets an
attribute based on a name and value, optionally creating the attribute if it
doesn't already exist.

lib/oga/xml/element.rb

@@ -96,6 +96,48 @@ module Oga
         return found ? found.value : nil
       end
 
+      ##
+      # Adds a new attribute to the element.
+      #
+      # @param [Oga::XML::Attribute] attribute
+      #
+      def add_attribute(attribute)
+        attribute.element = self
+
+        attributes << attribute
+      end
+
+      ##
+      # Sets the value of an attribute to the given value. If the attribute does
+      # not exist it is created automatically.
+      #
+      # @param [String] name The name of the attribute, optionally including the
+      #  namespace.
+      #
+      # @param [String] value The new value of the attribute.
+      #
+      def set(name, value)
+        found = attribute(name)
+
+        if found
+          found.value = value
+        else
+          if name.include?(':')
+            ns, name = name.split(':')
+          else
+            ns = nil
+          end
+
+          attr = Attribute.new(
+            :name           => name,
+            :namespace_name => ns,
+            :value          => value
+          )
+
+          add_attribute(attr)
+        end
+      end
+
       ##
       # Returns the namespace of the element.
       #

spec/oga/xml/element_spec.rb

@@ -101,6 +101,63 @@ describe Oga::XML::Element do
     end
   end
 
+  context '#add_attribute' do
+    before do
+      @element   = described_class.new
+      @attribute = Oga::XML::Attribute.new(:name => 'foo', :value => 'bar')
+    end
+
+    example 'add an Attribute to the element' do
+      @element.add_attribute(@attribute)
+
+      @element.attribute('foo').should == @attribute
+    end
+
+    example 'set the element of the attribute when adding it' do
+      @element.add_attribute(@attribute)
+
+      @attribute.element.should == @element
+    end
+  end
+
+  context '#set' do
+    before do
+      @element = described_class.new
+
+      @element.register_namespace('x', 'test')
+    end
+
+    example 'add a new attribute' do
+      @element.set('class', 'foo')
+
+      @element.get('class').should == 'foo'
+    end
+
+    example 'add a new attribute with a namespace' do
+      @element.set('x:bar', 'foo')
+
+      @element.get('x:bar').should == 'foo'
+    end
+
+    example 'set the namespace of an attribute' do
+      @element.set('x:bar', 'foo')
+
+      attr = @element.attribute('x:bar')
+
+      attr.namespace.is_a?(Oga::XML::Namespace).should == true
+    end
+
+    example 'overwrite the value of an existing attribute' do
+      attr = Oga::XML::Attribute.new(:name => 'foo', :value => 'bar')
+
+      @element.add_attribute(attr)
+
+      @element.set('foo', 'baz')
+
+      @element.get('foo').should == 'baz'
+    end
+  end
+
   context '#namespace' do
     before do
       @namespace = Oga::XML::Namespace.new(:name => 'x')