Welcome to Ruby. Yehuda Katz. Engine Yard

Transcription

1 Welcome to Ruby Yehuda Katz Engine Yard 1

2 Getting Started > Install JRuby > Add JRuby to Your Path > Start jirb 2 2

3 Everything is an Object > Numbers 8, 8.0, 0x8, 010, 0b1000 > Boolean true, false > Null nil > String hello, %[hello world ] 3 3

4 Blocks list = Array.new list.push 1 list.push 2 list.each { item puts item } 4 4

5 Blocks list = Array.new list.push 1 list.push 2 list.each do item puts item 5 5

6 Blocks list = Array.new list.push 1 list.push 2 list.each do item puts item => 1 => 2 6 6

7 3.times 3.times do puts "Hello" 7 7

8 3.times 3.times do puts "Hello" => Hello => Hello => Hello 8 8

9 def times def times i = 0 Integer: 3 while i < self yield i i += 1 self 9 9

10 def times def times i = 0 while i < self yield i puts "Hello" i += 1 self 10 10

11 Classes public class Writer { public static void write(string string) { System.out.println(string); } } 11 11

12 Classes class Writer def self.write(string) puts string 12 12

13 Classes public class Writer { public void write(string string) { System.out.println(string); } } new Writer().write("Hello"); 13 13

14 Classes class Writer def write(string) puts string Writer.new.write("Hello") 14 14

15 Classes class Writer def self.write(string) puts string write("in a class body") write(self.to_s) 15 15

16 Classes class Writer def self.write(string) puts string write("in a class body") write(self.to_s) => In a class body 16 16

17 Classes class Writer def self.write(string) puts string write("in a class body") write(self.to_s) => Writer 17 17

18 Reflection class Writer def self.arity(name) instance_method(name).arity rescue NameError "There is no method #{name}" puts arity("some_name") 18 18

19 Reflection class Writer def self.arity(name) instance_method(name).arity rescue NameError "There is no method #{name}" puts arity("some_name") => There is no method some_name 19 19

20 Reflection class Writer def self.arity(name) instance_method(name).arity rescue NameError "There is no method #{name}" puts Writer.arity("some_method") 20 20

21 Reflection class Writer def self.arity(name) instance_method(name).arity rescue NameError "There is no method #{name}" puts Writer.arity("some_method") => There is no method some_method 21 21

22 Reflection class Writer def hello puts "Hello World!" puts Writer.arity("hello") 22 22

23 Reflection class Writer def hello no arguments puts "Hello world" puts Writer.arity("hello") =>

24 Reflection class Writer def hello puts "Hello" puts Writer.instance_method("hello"). arity 24 24

25 Reflection class Writer def hello puts "Hello" puts Writer.instance_method("hello"). arity 25 25

26 Reflection class Writer def hello no arguments puts "Hello" puts Writer.instance_method("hello"). arity =>

27 Reflection class Writer def hello(name) puts "Hello #{name}" puts Writer.arity("hello") 27 27

28 Reflection class Writer def hello(name) puts "Hello #{name}" puts Writer.arity("hello") =>

29 Optional Arguments class Writer def hello(name = "JavaOne") puts "Hello #{name}" puts Writer.arity("hello") =>

30 Overloading public class Writer { public void hello() { hello("javaone"); } public void hello(string string) { System.out.println("Hello" + string); } } 30 30

31 Interfaces interface Printer { public void print(); public void print(string name); } 31 31

32 Interfaces public class Writer implements Printer { String defaultname; Writer() { defaultname = "JavaOne"; } Writer(String name) { defaultname = name; } public void print() { print(defaultname); } public void print(string str) { System.out.println(str); } } 32 32

33 Interfaces > Prototypes, not implementation > Used in type system > There's duplication when implementation is the same 33 33

34 Abstract Classes public abstract class Printer { String defaultname; Printer() { defaultname = "JavaOne"; } Printer(String name) { defaultname = name; } public void print() { print(defaultname); } public void print(string str) { System.out.println(str); } } 34 34

35 Abstract Classes public class Writer exts Printer { Writer(String name) { super(name); } public void hello() { hello(defaultname); } public void hello(string name) { print("hello" + name); } } 35 35

36 Abstract Classes > Full Implementations > Must be only superclass > Need to reiterate all-but-simple constructors 36 36

37 Ruby Modules module Printer def initialize(name = = name def write(str puts str 37 37

38 Ruby Modules module Printer def initialize(name = = name def write(str puts str 38 38

39 Ruby Modules module Printer def initialize(name = = name def write(str puts str 39 39

40 Ruby Modules module Printer def initialize(name = = name def write(str puts str 40 40

41 Ruby Modules module Printer def initialize(name = = name def write(str puts str 41 41

42 Ruby Modules class Writer include Printer def hello(name write "Hello #{name}" 42 42

43 Ruby Modules class Writer include Printer constructor mixed in from module def hello(name write "Hello #{name}" 43 43

44 Ruby Modules class Writer include Printer def hello(name write "Hello #{name}" 44 44

45 Ruby Modules class Writer include Printer def hello(name write "Hello #{name}" 45 45

46 Ruby Modules > Full implementations > Can have other superclasses > Can coexist with other modules > Can contain a constructor 46 46

47 Super class Printer def initialize(name = = name def write(str) puts str 47 47

48 Super module Yeller def write(str) str << "!" super Resolved at runtime 48 48

49 Super module Yeller def write(str) str << "!" super equivalent to super(str) 49 49

50 Super class HelloPrinter < Printer include Yeller def write(name super "Hello #{name}" 50 50

51 Super class HelloPrinter < Printer Printer include Yeller def write(name Yeller super "Hello #{name}" HelloPrinter 51 51

52 Super module Queryer def write(str) super("#{str}?") class HelloPrinter include Queryer 52 52

53 Super module Queryer Printer def write(str) super("#{str}?") Yeller Queryer class HelloPrinter include Queryer HelloPrinter 53 53

54 Super HelloPrinter.new.write Printer Yeller Queryer HelloPrinter 54 54

55 Super HelloPrinter.new.write Printer Yeller Queryer Hello JavaOne HelloPrinter 55 55

56 Super HelloPrinter.new.write Printer Yeller Hello JavaOne? Queryer Hello JavaOne HelloPrinter 56 56

57 Super HelloPrinter.new.write Printer Hello JavaOne?! Yeller Hello JavaOne? Queryer Hello JavaOne HelloPrinter 57 57

58 Super Printer Hello JavaOne!? Queryer Hello JavaOne! Yeller Hello JavaOne HelloPrinter 58 58

59 File I/O static void run(string in) throws FileNotFoundException { File input = new File(in); String line; Scanner reader = null; try { reader = new Scanner(input); while(reader.hasnextline()) { System.out.println(reader.nextLine()); } } finally { reader.close(); } } 59 59

60 File I/O static void run(string in) throws FileNotFoundException { File input = new File(in); String line; Scanner reader = null; try { reader = new Scanner(input); while(reader.hasnextline()) { System.out.println(reader.nextLine()); } } finally { reader.close(); } } 60 60

61 File I/O static void run(string in) throws FileNotFoundException { File input = new File(in); String line; Scanner reader = null; try { reader = new Scanner(input); while(reader.hasnextline()) { System.out.println(reader.nextLine()); } } finally { reader.close(); } } 61 61

62 File I/O static void run(string in) throws FileNotFoundException { File input = new File(in); String line; Scanner reader = null; try { reader = new Scanner(input); while(reader.hasnextline()) { System.out.println(reader.nextLine()); } } finally { reader.close(); } } 62 62

63 File I/O static void run(string in) throws FileNotFoundException { File input = new File(in); String line; Scanner reader = null; try { reader = new Scanner(input); while(reader.hasnextline()) { System.out.println(reader.nextLine()); } } finally { reader.close(); } } 63 63

64 File I/O static void run(string in) throws FileNotFoundException { File input = new File(in); String line; Scanner reader = null; try { reader = new Scanner(input); while(reader.hasnextline()) { System.out.println(reader.nextLine()); } } finally { reader.close(); } } 64 64

65 File I/O def run(input) File.open(input, "r") do f f.each_line { line puts line } 65 65

66 File I/O def run(input) File.open(input, "r") do f f.each_line { line puts line } 66 66

67 File I/O def run(input) File.open(input, "r") do f f.each_line { line puts line } 67 67

68 File I/O def run(input) File.open(input, "r") do f f.each_line { line puts line } 68 68

69 Open Classes class File def self.each_line(file) open(file, "r") do f f.each_line { line yield line } 69 69

70 Open Classes def File.each_line(file) open(file, "r") do f f.each_line { line yield line } 70 70

71 Revised def run(input) File.each_line(input) do line puts line 71 71

72 Revised def run(input) File.each_line(input) do line puts line Closing handled automatically 72 72

73 Servlets import java.io.*; import javax.servlet.*; import javax.servlet.http.*; public class HelloWorld exts HttpServlet { public void doget(httpservletrequest request, HttpServletResponse response) throws ServletException, IOException { PrintWriter out = response.getwriter(); out.println("hello World"); } } 73 73

74 Sinatra require 'rubygems' require 'sinatra' get '/' do "Hello World" 74 74

75 Servlets import java.io.*; import javax.servlet.*; import javax.servlet.http.*; public class HelloWWW exts HttpServlet { public void doget(httpservletrequest request, HttpServletResponse response) throws ServletException, IOException { response.setcontenttype("application/xml"); PrintWriter out = response.getwriter(); out.println("<hello>world</hello>"); } } 75 75

76 Web require 'rubygems' require 'sinatra' get '/' do content_type :xml "<hello>world</hello>" 76 76

77 Web require 'rubygems' require 'sinatra' get '/:name' do content_type :xml "<hello>#{params[:name]}</hello>" 77 77

78 RubyGems > gem list sinatra --remote > gem install sinatra > gem install sinatra -i gems > require "sinatra" 78 78

79 Yehuda Katz 79