Which is best, iteration or recursion?

breadcrumbs.rb

# I originally refactored this method to a recursive solution, but I wonder whether
# that's really necessary. Is the alternative approach using inject easier to
# understand?


# Original method, with external iterator:

# Build breadcrumb list from an array of nested model instances, starting with the parent
# and ending with the lowest level child. Each breadcrumb needs to be created using a
# sub-array containing itself and its parents.
def build_breadcrumb_list model_hierarchy
  output = []
  while model_hierarchy.any? do
    output << create_breadcrumb(model_hierarchy)
    model_hierarchy.delete_at(-1)
  end
  output << root_breadcrumb
  output.reverse.to_s.html_safe
end


# Refactored recursive version:

def build_breadcrumb_list model_hierarchy
  if model_hierarchy.empty?
    root_breadcrumb
  else
    build_breadcrumb_list(model_hierarchy[0..-2]) + create_breadcrumb(model_hierarchy)
  end
end


# Refactored again to use inject instead:

def build_breadcrumb_list model_hierarchy
  (1..model_hierarchy.length).inject(root_breadcrumb) do |out, n|
    out << create_breadcrumb(model_hierarchy[0, n])
  end
end


# So, which do you prefer? Is there a better way than either?

Might be of use:
https://github.com/GnomesLab/archive_tree

Personally I think I prefer the inject version; I find that a little more readable.