Ruby Variable Scope 簡單講解

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

以一個簡單例子示例各種變量的區別：

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中進入此文件所在文件夾，假設此文件名位test.rb，輸入 ruby test.rb 運行此文件，得到如下結果：