[Ruby] 深入分析Ruby 变量

  

• 一般小写字母、下划线开头：变量（Variable）。  
  
• $开头：全局变量（Global variable）。  
  
• @开头：实例变量（Instance variable）。  
  
• @@开头：类变量（Class variable）类变量被共享在整个继承链中  
  
• 大写字母开头：常数（Constant）。
  

#!/usr/bin/ruby
# -*- coding: UTF-8 -*-
 
$global_variable = 10
class Class1
 def print_global
   puts "全局变量在 Class1 中输出为 #$global_variable"
 end
end
class Class2
 def print_global
   puts "全局变量在 Class2 中输出为 #$global_variable"
 end
end
 
class1obj = Class1.new
class1obj.print_global
class2obj = Class2.new
class2obj.print_global

　　全局变量在 Class1 中输出为 10
全局变量在 Class2 中输出为 10

#!/usr/bin/ruby
 
class Customer
  def initialize(id, name, addr)
   @cust_id=id
   @cust_name=name
   @cust_addr=addr
  end
  def display_details()
   puts "Customer id #@cust_id"
   puts "Customer name #@cust_name"
   puts "Customer address #@cust_addr"
  end
end
 
# 创建对象
cust1=Customer.new("1", "John", "Wisdom Apartments, Ludhiya")
cust2=Customer.new("2", "Poul", "New Empire road, Khandala")
 
# 调用方法
cust1.display_details()
cust2.display_details()

　　Customer id 1
Customer name John
Customer address Wisdom Apartments, Ludhiya
Customer id 2
Customer name Poul
Customer address New Empire road, Khandala

#!/usr/bin/ruby
 
class Customer
  @@no_of_customers=0
  def initialize(id, name, addr)
   @cust_id=id
   @cust_name=name
   @cust_addr=addr
  end
  def display_details()
   puts "Customer id #@cust_id"
   puts "Customer name #@cust_name"
   puts "Customer address #@cust_addr"
  end
  def total_no_of_customers()
  @@no_of_customers += 1
  puts "Total number of customers: #@@no_of_customers"
  end
end
 
# 创建对象
cust1=Customer.new("1", "John", "Wisdom Apartments, Ludhiya")
cust2=Customer.new("2", "Poul", "New Empire road, Khandala")
 
# 调用方法
cust1.total_no_of_customers()
cust2.total_no_of_customers()

　　Total number of customers: 1
Total number of customers: 2

#!/usr/bin/ruby
# -*- coding: UTF-8 -*-
 
class Example
  VAR1 = 100
  VAR2 = 200
  def show
  puts "第一个常量的值为 #{VAR1}"
  puts "第二个常量的值为 #{VAR2}"
  end
end
 
# 创建对象
object=Example.new()
object.show

　　第一个常量的值为 100
第二个常量的值为 200

  

• self: 当前方法的接收器对象。  
  
• true: 代表 true 的值。  
  
• false: 代表 false 的值。  
  
• nil: 代表 undefined 的值。  
  
• __FILE__: 当前源文件的名称。  
  
• __LINE__: 当前行在源文件中的编号。