ruby memo

<br />to_i(9)<br />gets<br />File.read("cc.txt")<br /><br />fh = File.new("cc.txt", "w")<br />fh.puts f<br />fh.close<br /><br />require just once<br />load will force reload<br /><br />ruby -l demo.rb<br />ruby-1.6.8 -ve ...............<br />sudo gem updateh<br /><br />sort_by<br />sort<br />-------------------------------------------------------------------------------<br />application layout no effect<br /><br />apache config set the request go the where<br />Document /home/lake/rails_app/iwakela/public<br />public have a .htaccess will define which dispatch will be used<br /><br />controller could use CGI and some data in form => use params method<br /> session => use session method<br /><br />玩弄YAML "string".to_yaml<br />YAML.load(<yaml_type>)<br />XML<br />JSON<br /><br />lambda block,<br />sort_proc = lambda{|e| [e................]}<br />呼叫 &sort_proc<br /><br />ruby -e 'p Dir["*.rb"]'<br /><br />puts "ccc" #return nil<br /><br />-------------------------------------------------------------------------------<br /> Object.new.methods.sort<br /><br />>> u.send(name)<br />NameError: undefined local variable or method `name' for #<Object:0xb7d2d9a0><br /> from (irb):10<br />>> u.send(:name)<br />=> "早鳥"<br />>> u.send("name")<br />=> "早鳥"<br /><br />>> u.respond_to?(name)<br />NameError: undefined local variable or method `name' for #<Object:0xb7d2d9a0><br /> from (irb):12<br />>> u.respond_to?(:name)<br />=> true<br />>> u.respond_to?("name")<br />=> true<br /><br /><br />ruby's variable would not take the object's content directly , they just take the reference<br /><br />new initialize<br />superclass<br /><br />------------------------------<br />Singleton -> C -> M -> C -> M<br /><br />super<br /><br />------------------------------<br />instance method, self be known in run time<br /><br />singleton in particulr object(could be class object, too)<br /><br />class function is singleton function, too<br />self.x = C.x<br />singletion give us a chance to add new method in run time<br /><br />some situation dot could not be ingored, self.venue = blahblah<br /><br />$0 is the file name be executed<br /><br />inner method could not take the outer scope variable<br />class C<br /> aa = 1<br /> def m<br /> p aa<br /> end<br /><br /> p aa<br />end<br /><br /><br />bareword, private method, <br />def aa<br /> p 'aaa'<br />end<br />aa<br /><br />,and puts, print are either<br />-----------------------------------<br /><br />whem, ===<br /><br />yield, block<br />[Q]: Why need code block <br />[A]: We could call the same function, but we could use different block to achieve different goal<br />yield, block both skills for using function like parameter<br /><br />rescue Errno::ENOENT => e<br /><br />-----------------------------------------<br />strip : lose the outer spaces<br />chop : remove last character<br />chomp : remove training newline<br /><br />eql? is more like ==<br />equal? test two object is the same or not<br /><br />:"Symbol need the quote if it has spaces"<br /><br />--------------------------------------------<br />Array.new(3, "abc") would be all the same object<br />Array.new(3){"abc"} that would be different objects<br /><br />add<br />unshift[.........]push<br /><br />remove<br />shift[............]pull return the element be removed<br /><br />[Q]: concat push, what is the different? <br />[A]: concat would sort, push would just add to the array tailer<br /><br />replcae is change the content of the original object<br /><br />>> [1,2,3].zip([4,5,6])<br />=> [[1, 4], [2, 5], [3, 6]]<br />>> [1,2,3].zip([4,5,6]).flatten<br />=> [1, 4, 2, 5, 3, 6]<br />>> [1,2,3].zip([4,5,6]).flatten.join<br />=> "142536"<br />>> [1,2,3].zip([4,5,6]).flatten.join(", ")<br />=> "1, 4, 2, 5, 3, 6"<br />>> [1,2,3].zip([6,2,3]).flatten.uniq<br />=> [1, 6, 2, 3]<br /><br />-----------------------------------------------------<br />find<br />find_all (select)<br />include?<br />reject<br /><br />>> User.find(:all, :conditions => "name like '%'").map(&:name)<br />=> ["早鳥", "flake", "flak", "lakela", "sandy", "lakela1", "什麼鬼什麼鬼什麼鬼啊啦", "lake.ilakela2", "lake+iwakela", "ilakelaaa"]<br />>> User.find(:all, :conditions => "name like 'lake'").map(&:name)<br />=> []<br />>> User.find(:all, :conditions => "name like 'lake%'").map(&:name)<br />=> ["lakela", "lakela1", "lake.ilakela2", "lake+iwakela"]<br />>> User.find(:all, :conditions => "name like 'lak%'").map(&:name)<br />=> ["lakela", "lakela1", "lake.ilakela2", "lake+iwakela"]<br />>> User.find(:all, :conditions => "name like '%lak%'").map(&:name)<br />=> ["flake", "flak", "lakela", "lakela1", "lake.ilakela2", "lake+iwakela", "ilakelaaa"]<br /><br />>> User.find(:all).find_all{|u| /^lake/.match(u.name)}.map(&:name)<br />=> ["lakela", "lakela1", "lake.ilakela2", "lake+iwakela"]<br />>> User.find(:all).find_all{|u| /lake/.match(u.name)}.map(&:name)<br />=> ["flake", "lakela", "lakela1", "lake.ilakela2", "lake+iwakela", "ilakelaaa"]<br /><br /><br /><br />>> h = {"a" => 1, "b" => 2, "c" => 3}<br />=> {"a"=>1, "b"=>2, "c"=>3}<br />>> h.values_at("a", "b")<br />=> [1, 2]<br />>> h["d"]<br />=> nil<br />>> h.fetch("d")<br />IndexError: key not found<br /> from (irb):17:in `fetch'<br /> from (irb):17<br /> from :0<br /><br /><br />Hash.new{block} block would be executed when access key does not exist<br />>> h = Hash.new{|hash, key| hash[key] = key }<br />=> {}<br />>> h["lake"]<br />=> "lake"<br />>> h<br />=> {"lake"=>"lake"}<br /><br />>> h<br />=> {"flake"=>"flake", "lake"=>"lake"}<br />>> h2<br />=> {"lake"=>"lakelake"}<br />>> h3 = h.merge(h2)<br />=> {"flake"=>"flake", "lake"=>"lakelake"}<br /><br />>> h3.invert<br />=> {"lakelake"=>"lake", "flake"=>"flake"}<br /><br />>> h3.replace(h3.invert)<br />=> {"flake"=>"flake", "lake"=>"lakelake"}<br />>> h3.clear<br />=> {}<br />>> h3<br />=> {}<br /><br />>> h4 = h.merge(h2)<br />=> {"flake"=>"flake", "lake"=>"lakelake"}<br />>> h4.keys<br />=> ["flake", "lake"]<br />>> h4.values<br />=> ["flake", "lakelake"]<br /><br />>> { 1 => "a", 2 => "b"}.find_all{|k, v| k%2 == 0}<br />=> [[2, "b"]]<br />become array<br /><br />>> { 1 => "a", 2 => "b"}.map{|k, v| [k*2, v.upcase]}<br />=> [[2, "A"], [4, "B"]]<br /><br />>> h.has_key?(1)<br />=> true<br />>> h.has_value?(1)<br />=> false<br /><br /><br />sort<br /><=><br /><br />>> User.find(:all).map(&:name).sort<br />=> ["flak", "flake", "ilakelaaa", "lake+iwakela", "lake.ilakela2", "lakela", "lakela1", "sandy", "什麼鬼什麼鬼 什麼鬼啊啦", "早鳥"]<br />>> User.find(:all).map(&:name).sort do |a,b|; a.size <=> b.size;end<br />=> ["flak", "flake", "sandy", "lakela", "早鳥", "lakela1", "ilakelaaa", "lake+iwakela", "lake.ilakela2", "什麼 鬼什麼鬼什麼鬼啊啦"]<br /><br />We could overwrite the <=> by a block <br /><br />>> User.find(:all).map(&:name).sort_by do |a|; a.size;end<br />=> ["flak", "flake", "sandy", "lakela", "早鳥", "lakela1", "ilakelaaa", "lake+iwakela", "lake.ilakela2", "什麼 鬼什麼鬼什麼鬼啊啦"]<br /><br /><br />-------------------------------------------<br />>> 'abc def' =~ /a/<br />=> 0<br />>> /a/ =~ 'abc def'<br />=> 0<br />>> /g/ =~ 'abc def'<br />=> nil<br />>> 'abc def' =~ /g/<br />=> nil<br /><br />Regexp stay in left or right is the same<br />if match, it would return the location of string, or return nil<br />>> /a/.match('abc def')<br />=> #<MatchData:0xb75f6da8><br />>> ('abc def').match(/a/)<br />=> #<MatchData:0xb75f1128><br /><br />>> m = 'ABClake.ilakela@gmail.com'.match(/([_a-z0-9-]+)(\.[_a-z0-9-]+)*(\+[_a-z0-9-]+)*@([a-z0-9-]+)(\.[a-z0-9-]+)*(\.[a-z]{2,4})$/)<br />=> #<MatchData:0xb759f1ac><br />>> m[0]<br />=> "lake.ilakela@gmail.com"<br />>> m[1]<br />=> "lake"<br />>> m[2]<br />=> ".ilakela"<br />>> m.captures[0]<br />=> "lake"<br />>> m.captures[1]<br />=> ".ilakela"<br /><br />$& match 到的 m[0]<br />$` match到 前面的string m.pre_match<br />$' match到 後面的string m.post_match<br />$1 $2 第1 ,2個() 裡面的東西 m[1], m[2]<br /><br />.>> m.begin(1) the first capture begin at location<br />=> 3<br />>> m.end(1)<br />=> 7<br /><br /><br />>> m = 'abc!def!ika!'.match(/.+!/)<br />=> #<MatchData:0xb753d614><br />>> m[0]<br />=> "abc!def!ika!"<br />>> m = 'abc!def!ika!'.match(/.+?!/)<br />=> #<MatchData:0xb753944c><br />>> m[0]<br />=> "abc!"<br /><br />add ? after +<br /><br />>> m = 'abc!def!ikdda!'.match(/\w{4}+!/)<br />=> #<MatchData:0xb7529344><br />>> m[0]<br /><br />>> m = 'abc!def!ikdda!'.match(/.{4,5}!/)<br />=> #<MatchData:0xb74f150c><br />>> m[0]<br />=> "c!def!"<br /><br />>> m = 'a3b4c5'.match(/([a-z]\d){2}/)<br />=> #<MatchData:0xb74c3468><br />>> m[0]<br />=> "a3b4"<br /><br /><br />>> m = 'abc def. gga'.match(/[a-z]+(?=\.)/)<br />=> #<MatchData:0xb74bcf3c><br />>> m[0]<br />=> "def"<br />>> m = 'abc def. gga'.match(/[a-z]+(?!\s)/)<br />=> #<MatchData:0xb74ac2f4><br />>> m[0]<br />=> "ab"<br /><br /><br />>> "a,b;c#d".split(/,|;|#/)<br />=> ["a", "b", "c", "d"]<br />>> "a,b;c#d".split(/,|;|#/, 2)<br />=> ["a", "b;c#d"]<br />>> "a,b;c#d".split(/,|;|#/, 3)<br />=> ["a", "b", "c#d"]<br /><br /><br />>> "a,bd,gre,gef,a".sub(/\w{3}(?=,)/) {|s| s.upcase}<br />=> "a,bd,GRE,gef,a"<br /><br />>> "a,bd,greGEF,a".sub(/(\w{3})([A-Z]{3})/, '\2\1') <br />=> "a,bd,GEFgre,a"<br /><br /><br /><br />>> ["ab", "bcd", "efg"].grep(/\w{3}/) {|w| w.upcase}<br />=> ["BCD", "EFG"]<br /><br />>> ["ab", "bcd", "efg"].select {|w| p w.upcase if w.match(/\w{3}/) }<br />"BCD"<br />"EFG"<br />=> []<br />>> ["ab", "bcd", "efg"].select {|w| w.upcase if w.match(/\w{3}/) }<br />=> ["bcd", "efg"]<br /><br />>> ["ab", "bcd", "efg"].map {|w| w.upcase if w.match(/\w{3}/) }<br />=> [nil, "BCD", "EFG"]<br /><br /><br />>> ["1","2",3].grep(/\d/)<br />=> ["1", "2"]<br /><br />--------------------------------<br />Proc.new is different from lambde in return scope<br /><br />const_set<br /><br /> alias_method :old_destroy, :destroy<br /><br /> def destroy(r)<br /> if r<br /> old_destroy<br /> else<br /> update_attribute(:removed_at, Time.now) if !removed_at<br /> end<br /> end<br /><br />----------------------------------<br />class Work < ActiveRecord::Base<br /> belongs_to :composer<br /><br /> def composer<br /> Composer.find(composer_id)<br /> end<br />end<br /><br /><br /><br />Returns a copy of self with all nil elements removed.<br /><br /> [ "a", nil, "b", nil, "c", nil ].compact<br /> #=> [ "a", "b", "c" ]<br /><br />-------------------------------------<br />Association callbacks, before_add, after_add, before_remove and after_remove<br /><br /> module FindOrCreateByNameExtension<br /> def find_or_create_by_name(name)<br /> first_name, last_name = name.split(" ", 2)<br /> find_or_create_by_first_name_and_last_name(first_name, last_name)<br /> end<br /> end<br /><br /> class Account < ActiveRecord::Base<br /> has_many :people, :extend => FindOrCreateByNameExtension<br /> end<br /><br /> class Company < ActiveRecord::Base<br /> has_many :people, :extend => FindOrCreateByNameExtension<br /> end<br /><br /><br /> class Account < ActiveRecord::Base<br /> has_many :people, :extend => [FindOrCreateByNameExtension, FindRecentExtension]<br /> end<br /><br /><br />Post.find(:all, :include => [ :author, :comments ])<br />Post.find(:all, :include => [ :author, { :comments => { :author => :gravatar } } ])<br />Post.find(:all, :include => [ :author, :comments ], :conditions => ['comments.approved = ?', true])<br />