Experience Ruby in 20 minutes

1 #! /Usr/bin/ENV Ruby
2
3 class megagreeter
4 attr_accessor: names // sets attributes. Two methods (name, name =) are automatically generated to access the value of @ name.
// What methods does a class provide? Class Name. instance_methods will tell you that if you only want to know the method you have defined, add a false parameter.
5
6 # create the object
7 def initialize (names = "world") // Constructor
8 @ names = names // defines the local variable @ names
9 end
10
11 # Say hi to everybody
12 def say_hi
13 if @ names. nil? // Determine whether @ names is nil
14 puts "" // output
15 elsif @ names. respond_to? ("Each") // determine whether @ names has an each method
16
17 # @ names is a list of some kind, iterate!
18 @ names. Each do | Name | // Loop
19 puts "hello # {name }! "
20 end
21 else
22 puts "hello # {@ names }! "
23 end
24 end
25
26 # Say bye to everybody
27 def say_bye
28 If @ names. nil?
29 puts ""
30 elsif @ names. respond_to? ("Join ")
31 # Join the list elements with commas
32 puts "goodbye # {@ names. Join (", ")}. Come back soon! "
33 else
34 puts "goodbye # {@ names}. Come back soon! "
35 end
36 end
37
38end
39
40
41if _ file _ = $0 // _ file _ name of the currently running script file, $0Is the name of the startup script.
// This allows the code to be called as a database without running the startup code,
The startup code is called when the script is executed.
42 mg = megagreeter. New
43 mg. say_hi
44 mg. say_bye
45
46 # Change name to be "Zeke"
47 mg. Names = "Zeke"
48 mg. say_hi
49 mg. say_bye
50
51 # change the name to an array of names
52 mg. Names = ["Albert", "Brenda", "Charles ",
53 "Dave", "Englebert"]
54 mg. say_hi
55 mg. say_bye
56
57 # change to nil
58 mg. Names = Nil
59 mg. say_hi
60 mg. say_bye
61end