This fall in our Bainbridge Island reading group, we are going through the Ruby on Rails and Ruby (Pickaxe) book. At our last meeting, one of the things that we discussed was Ruby closures, and I was trying to help people understand what was going on. Turns out there was one area where I didn't quite understand what was going on: the ability to pass an existing function as a block argument. I thought that you'd be able to do that, but apparently you can't.

A few days afterwards I finally got around to reading this post by Dave Thomas on the Symbol#to_proc hack, which I've excerpted:

The Ruby Extensions Project contains an absolutely wonderful hack. Say you want to convert an array of strings to uppercase. You could write

result = names.map {|name| name.upcase}

Fairly concise, right? Return a new array where each element is the corresponding element in the original, converted to uppercase. But if you include the Symbol extension from the Ruby Extensions Project, you could instead write

result = names.map(&:upcase)

Now that’s concise: apply the upcase method to each element of names.

Ouch. My idea of concise would have been:

result = names.map(upcase)

Or am I missing something here?