They are both equivalent in terms of functionality. The first is a common rails idiom:
@some_collection.collect(&:id) or @some_collection.map(&:id) #I've seen this one used more than collect... The ampersand syntax is simply telling the interpreter that the symbol is the block parameter to the method. Internally the to_proc method of the symbol class is called. Here's a reference: http://apidock.com/rails/Symbol/to_proc Beware, doing @foo.map(&:id) doesn't perform as well as @foo.map { |f| f.id } for big numbers of foos... Also note that this is a Rails only feature (ie: try it on plain irb and it will not work). On Mar 11, 1:35 pm, Hiro Protagonist <rails-mailing-l...@andreas- s.net> wrote: > Hi all, > Can someone explain to me in terms of ruby why this works? > > Story.find_all_by_user_id(2).collect(&:link) # 1 method call > > This is in ROR console. link is a property of Story. The above command > finds all db rows and all their properties (columns) with user_id == 2 > and creates an array with only the link property. > > This is same as: > Story.find_all_by_user_id(2).collect{|x| x.link} # 2 block > > I understand function #2 with use of a block. > > I do not understand function #1 in terms of syntax. What is &:link? I > know it represents a property and could accept that this is the way it > works but I want to understand this in terms of ruby syntax. Is &:link > a block? If so it would have to represent x.link. I do not understand > how this is generated in ruby. > > TIA, > Pete > -- > Posted viahttp://www.ruby-forum.com/. --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Ruby on Rails: Talk" group. To post to this group, send email to rubyonrails-talk@googlegroups.com To unsubscribe from this group, send email to rubyonrails-talk+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en -~----------~----~----~----~------~----~------~--~---
