How do I pass a block and an initial argument to each in Ruby?

Question

I use data-tip for every HTML element to show a tooltip if it has this property.

Since

data_tip: "a message for you"

looks much nicer than

:"data-tip" => "an other message for rudi"

I convert '_' to '-' wherever I am responsible for that.

For my simple navigation gem menu I found a nice recursive solution:

cleanup=Proc.new do |item|
  cleanup_hash item.html_options #<- this does the '_' -> '-'
  item.sub_navigation.items.each(&cleanup) if item.sub_navigation
end
navigation.primary_navigation.items.each(&cleanup)

This works great, but, what if I want to print out the nesting level? Where do I put the starting '0'?

Answer 1

You can use curry

cleanup=Proc.new do |depth=0, item|
  cleanup_hash item.html_options #<- this does the '_' -> '-'
  item.sub_navigation.items.each(&cleanup.curry[depth + 1]) if item.sub_navigation
end
navigation.primary_navigation.items.each(&cleanup)

What curry does:

A curried proc receives some arguments. If a sufficient number of arguments are supplied, it passes the supplied arguments to the original proc and returns the result. Otherwise, returns another curried proc that takes the rest of arguments.