1 #全局变量
2 $global_variable=10
3 class Class1
4     def print_global()
5         puts "Global variable in Class1 is #{$global_variable}"
6     end
7 end
8 class1obj=Class1.new
9 class1obj.print_global()

 1 #实例变量
 2 class Customer
 3     def initialize(id,name,addr)
 4         @cust_id=id
 5         @cust_name=name 
 6         @cust_addr=addr
 7     end
 8     def display_detalis
 9         puts "Customer id #{@cust_id}"
10         puts "Customer name #{@cust_name}"
11         puts "Customer addr #{@cust_addr}"
12     end
13 end
14 cust1=Customer.new("1","John","Wisdom")
15 cust1.display_detalis

 1 #类变量
 2 class Customer
 3     @@no_of_customers=0
 4     def initialize(id,name,addr)
 5         @cust_id=id
 6         @cust_name=name
 7         @cust_addr=addr
 8     end
 9     def display_details()
10         puts "Customer id #{@cust_id}"
11         puts "Customer name #{@cust_name}"
12         puts "Customer addr #{@cust_addr}"
13     end
14     def total_no_of_customers()
15         @@no_of_customers +=1
16         puts "Totla number of customers:#{@@no_of_customers}"
17     end
18 end
19 cust1=Customer.new("1","John","Wisdom")
20 cust2=Customer.new("2","Poul","New")
21 
22 cust1.total_no_of_customers
23 cust2.total_no_of_customers