Iterate through sorted Hash keys

[XMol]

Who hasn't run into that use-case? You want to iterate through the keys of a Hash in order and the usual solution to that is $hash.keys.sort.each |$key| { $value = $hash[$key] }. This idiom was very common especially for templates with older Puppet versions, where iteration of Hashes wasn't guaranteed to be idempotent. However, I still like to dump Hashes in key-order, so the output is scanable for specific keys. With inspiration from Puppet's own each() function, I came up with...

Puppet::Functions.create_function(:each_with_sorted_keys) do
  dispatch :on_hash do
    param 'Hash[Variant[Scalar, Array], Any]', :hash
    block_param 'Callable[2,2]', :block
  end

  def on_hash (hash)
    enumerator = hash.keys.sort.each
    begin
      while (k = enumerator.next) do
        yield(k, hash[k])
      end
    rescue StopIteration
    end
    # produces the receiver
    hash
  end
end

Use this function in EPP templates like this:

<% each_with_sorted_keys($hash) |$k, $v| { -%>
<%= $k %>: <%= $v %>
<% } -%>

... just like basic each, though the output will be sorted according to the keys!