Ignore differences in attribute order?

[bhollis]

The order of attributes on an element shouldn't result in a diff, should they?

[bhollis]

Never mind, something else was going on.

[bhollis]

Oh, actually, this actually is a problem.

Repro:

require 'nokogiri'
require 'nokogiri/diff'

x = Nokogiri::XML("<foo a='a' b='b'></foo>")
y = Nokogiri::XML("<foo b='b' a='a'></foo>")

x.diff(y) do |change, node|
  puts "#{change} #{node.inspect}\n"
end

Output:

  #<Nokogiri::XML::Element:0x3ffbdd4df5a8 name="foo" attributes=[#<Nokogiri::XML::Attr:0x3ffbdd4defcc name="a" value="a">, #<Nokogiri::XML::Attr:0x3ffbdd4defb8 name="b" value="b">]>
- #<Nokogiri::XML::Attr:0x3ffbdd4defcc name="a" value="a">
  #<Nokogiri::XML::Attr:0x3ffbdd4defb8 name="b" value="b">
+ #<Nokogiri::XML::Attr:0x3ffbdd4de810 name="a" value="a">
  #<Nokogiri::XML::Text:0x3ffbdcc89908 "b">

I can fix it by patching tdiff_each_child, but I'm not sure if it should be an option or something:

def tdiff_each_child(node,&block)
  if node.kind_of?(Nokogiri::XML::Element)
    node.attribute_nodes.sort {|a,b| a.name <=> b.name }.each(&block)
  end

  node.children.each(&block)
end

[postmodern]

OTOH, difference in order implies something changed in the rendering of the HTML.

[bhollis]

Definitely. But I think in the XML model, the order of attributes doesn't matter - just the presence and value of the attributes. I know when you canonicalize a document attributes end up sorted. That's why I don't know if this should be a general fix or an option.

[leehambley]

FWIW I'd be on the side of not caring about attribute order.

[postmodern]

OK, there is a case for ignoring the order. Now how do we accomplish this with the current tsort algorithm?

[bhollis]

I think the modified tdiff_each_child I posted works.

[postmodern]

Alright I will add your code and write some specs for this new behaviour.

[bhollis]

Thanks!

[postmodern]

Released in 0.2.0.