David's Blog

Many rubyists are familiar with the following shorthand:

# normal
collection.each {|obj| obj.delete}

# shorthand
collection.each(&:delete)

This shorthand makes it easy to send each element of an enumerator a specific message.

But what if you want to send each element of your collection to a method on another object?

For example, what if you had an array of bill amounts and you wanted to map this to an array of Bill objects? You could:

amounts.map do |amount|
  Bill.new(amount)
end

The short way to do this, however, is this:

amounts.map(&Bill.method(:new))

Just a cool trick!