ruby 使用Struct场景

替代类使用，节省代码，清晰简洁

使用Struct

SelectOption = Struct.new(:display, :value) do
def to_ary
[display, value]
end
end

option_struct = SelectOption.new("Canada (CAD)", :cad)

puts option_struct.display
# Canada (CAD)
puts option_struct.to_ary.inspect
# ["Canada (CAD)", :cad]

使用类
class SelectOption

attr_accessor :display, :value

def initialize(display, value)
@display = display
@value = value
end

def to_ary
[display, value]
end

end

option_struct = SelectOption.new("USA (USD)", :usd)

puts option_struct.display
# USA (USD)
puts option_struct.to_ary.inspect
# ["USA (USD)", :usd]

临时的数据结构

例如一个使用两个日期来过滤表单数据的例子，你可以在过滤的地方使用两个值，也可以创建一个FilterRange Struct结构， 这个结构有一个from_date和to_date属性， 你或许需要一个方法来统计两个日期间的数据，你也可以穿件一个类，但是用struct更简单，同时帮你清理代码

require 'ostruct'
require 'date'

SelectOption = Struct.new(:from_date, :to_date) do
def filter_data(date)

return  true if date>=from_date..date<=to_date

end
end

option_struct = SelectOption.new(Time.now, Time.now+10)

p option_struct.filter_data(Time.now+4)

类内部数据

class Person

Address = Struct.new(:street_1, :street_2, :city, :province, :country, :postal_code)

attr_accessor :name, :address

def initialize(name, opts)
@name = name
@address = Address.new(opts[:street_1], opts[:street_2], opts[:city], opts[:province], opts[:country], opts[:postal_code])
end

end

leigh = Person.new("Leigh Halliday", {
street_1: "123 Road",
city: "Toronto",
province: "Ontario",
country: "Canada",
postal_code: "M5E 0A3"
})

puts leigh.address.inspect
# <struct Person::Address street_1="123 Road", street_2=nil, city="Toronto", province="Ontario", country="Canada", postal_code="M5E 0A3">

作为测试使用的Stub

KCup = Struct.new(:size, :brewing_time, :brewing_temp)
colombian = KCup.new(:small, 60, 85)

brewer = Brewer.new(colombian)
expect(brewer.brew).to eq(true)

Struct相比较penstruct，速度快， 但是openStruct可以动态添加属性，

australia = OpenStruct.new(:country => "Australia", :population => 20_000_000)

australia.name='jack'

p australia