{"id":67,"date":"2008-03-02T11:21:37","date_gmt":"2008-03-02T19:21:37","guid":{"rendered":"http:\/\/fernyb.net\/blog\/2008\/03\/02\/ruby-technique-meta-programming\/"},"modified":"2008-03-02T11:21:37","modified_gmt":"2008-03-02T19:21:37","slug":"ruby-technique-meta-programming","status":"publish","type":"post","link":"http:\/\/fernyb.net\/blog\/2008\/03\/02\/ruby-technique-meta-programming\/","title":{"rendered":"Ruby Technique: Meta Programming"},"content":{"rendered":"

\nMeta Programming is code that writes code. See the code sample below.
\nI have made a screencast of this process. View it here<\/a>\n<\/p>\n

\n
\n
#!\/usr\/bin\/env ruby<\/span>\r\n\r\nclass <\/span>Product<\/span>\r\n  def <\/span>initialize<\/span>(<\/span>items<\/span>)<\/span>\r\n    items<\/span>.<\/span>each<\/span> {|<\/span>item<\/span>|<\/span> Product<\/span>.<\/span>product<\/span>(<\/span>item<\/span>)<\/span> }<\/span>\r\n  end<\/span>\r\n\r\n  def <\/span>self.product<\/span>(<\/span>item<\/span>)<\/span>\r\n    code<\/span> =<\/span> %Q{<\/span>\r\n      def add_#{item}<\/span>(item)\r\n        @#{item}<\/span> = [] unless @#{item}<\/span>\r\n        @#{item}<\/span> << item\r\n      end\r\n\r\n      def display_#{item}<\/span>s\r\n        @#{item}<\/span>.each {|item| puts item <\/span>}<\/span>\r\n      end<\/span>\r\n    }<\/span>\r\n    class_eval<\/span>(<\/span>code<\/span>)<\/span>\r\n  end<\/span>\r\nend<\/span>\r\n\r\nclass <\/span>Item<\/span> <<\/span> Product<\/span>\r\n  def <\/span>initialize<\/span>(*<\/span>items<\/span>)<\/span>\r\n    super<\/span>(<\/span>items<\/span>)<\/span>\r\n  end<\/span>\r\nend<\/span>\r\n\r\ncart<\/span> =<\/span> Item<\/span>.<\/span>new<\/span>(<\/span>:book<\/span>,<\/span> :computer<\/span>,<\/span> :music<\/span>)<\/span>\r\ncart<\/span>.<\/span>add_book<\/span>(<\/span>:Ruby<\/span>)<\/span> # => Add a book to our cart items<\/span>\r\n\r\ncart<\/span>.<\/span>display_books<\/span> # => We want to display All books we have added<\/span>\r\nputs<\/span> "<\/span>\\n<\/span><\/span>"<\/span>\r\n\r\ncart<\/span>.<\/span>add_computer<\/span>(<\/span>:Apple<\/span>)<\/span>\r\ncart<\/span>.<\/span>add_computer<\/span>(<\/span>:Dell<\/span>)<\/span>\r\ncart<\/span>.<\/span>add_computer<\/span>(<\/span>:Sony<\/span>)<\/span>\r\ncart<\/span>.<\/span>display_computers<\/span> # => Display All Computers<\/span>\r\nputs<\/span> "<\/span>\\n<\/span><\/span>"<\/span>\r\n\r\ncart<\/span>.<\/span>add_music<\/span>(’<\/span>Modest Mouse<\/span>‘)<\/span>\r\ncart<\/span>.<\/span>add_music<\/span>(’<\/span>Northstar<\/span>‘)<\/span>\r\ncart<\/span>.<\/span>display_musics<\/span> # => Display All Music Items<\/span>\r\n<\/pre>\n<\/div>\n<\/div>\n","protected":false},"excerpt":{"rendered":"
Meta Programming is code that writes code. See the code sample below. I have made a screencast of this process. View it here #!\/usr\/bin\/env ruby class Product def initialize(items) items.each {|item| Product.product(item) } end def self.product(item) code = %Q{ def add_#{item}(item) @#{item} = [] unless @#{item} @#{item} << item end def display_#{item}s @#{item}.each {|item| puts […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[3,21],"tags":[],"_links":{"self":[{"href":"http:\/\/fernyb.net\/blog\/wp-json\/wp\/v2\/posts\/67"}],"collection":[{"href":"http:\/\/fernyb.net\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/fernyb.net\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/fernyb.net\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/fernyb.net\/blog\/wp-json\/wp\/v2\/comments?post=67"}],"version-history":[{"count":0,"href":"http:\/\/fernyb.net\/blog\/wp-json\/wp\/v2\/posts\/67\/revisions"}],"wp:attachment":[{"href":"http:\/\/fernyb.net\/blog\/wp-json\/wp\/v2\/media?parent=67"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/fernyb.net\/blog\/wp-json\/wp\/v2\/categories?post=67"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/fernyb.net\/blog\/wp-json\/wp\/v2\/tags?post=67"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}