Ruby Variable Scope 简单讲解

最新推荐文章于 2021-12-12 20:20:29 发布

原创最新推荐文章于 2021-12-12 20:20:29 发布 · 1.2k 阅读

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#ruby #class #variable #scope #instance

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本文通过一个Ruby类的实例详细解释了不同类型的变量及其作用范围，包括全局变量、实例变量、局部变量、常量和类变量，并展示了这些变量如何在实际代码中被使用。

Name Begins With	Variable Scope
`$`	A global variable
`@`	An instance variable
`[a-z]` or `_`	A local variable
`[A-Z]`	A constant
`@@`	A class variable

以一个简单例子示例各种变量的区别：

class Female
	# Constant
	SEX = 'female'

	# Class variable: shared among all instances of this class
	@@sex = SEX

	def initialize( weight, height)
		# Instance variable: accessible to specific instance of this class
		@weight = weight
		@height = height
	end

	def self.sex
		@@sex
	end

	def description
		# Local variable: local to this block
		ideal_weight = @height * 0.8

		puts 'This female ideal weight would be ' + ideal_weight.to_s + ' and her actually weight is ' + @weight.to_s
	end

end


puts Female.new(130, 170).description
puts Female.sex

Console中进入此文件所在文件夹，假设此文件名位test.rb，输入 ruby test.rb 运行此文件，得到如下结果：