What does map(&:name) do in this Ruby code?
ruby, ruby-on-rails
Solution
events.map(&:name)
is exactly equivalent to
events.map{|x| x.name}
it is just convenient syntactic sugar.
For more details, check out the `Symbol#to_proc` method here. Here, `:name` is being coerced to a proc.
By the way, this comes up often here - it's just very hard to google or otherwise search for 'the colon thing with an ampersand' :).
Problem
Trying to understand Ruby a bit better, I ran into this code surfing the Internet: ``` require 'rubygems' require 'activeresource' ActiveResource::Base.logger = Logger.new("#{File.dirname(__FILE__)}/events.log") class Event < ActiveResource::Base self.site = "http://localhost:3000" end events = Event.find(:all) puts events.map(&:name) e = Event.find(1) e.price = 20.00 e.save e = Event.create(:name => "Shortest event evar!", :starts_at => 1.second.ago, :capacity => 25, :price => 10.00) e.destroy ``` What I'm particularly interested in is how does `events.map(&:name)` work? I see that events is an array, and thus it's invoking its map method. Now my question is, where is the block that's being passed to map created? What is the symbol :name in this context? I'm trying to understand how it works.