Question

所以我试图创建动态变量，然后再使用它们而不必输入全名。我制作的测试代码如下

players = [1, 2, 3, 4]

players.each |player|
  instance_variable_set("@player_#{player}_hand", "foo")
  instance_variable_set("@player_#{player}_value", "bar")
}

puts @player_1_hand # => foo
puts @player_3_value # => bar

players.each { |player| 
puts "@player_#{player}_hand" 
}

# => @player_1_hand
# => @player_2_hand
# => @player_3_hand
# => @player_4_hand

我想动态调用和/或更新这些变量，但在初始化之后我不知道该怎么做。我发现的文档更令人困惑而不是有用。有人可以解释如何正确使用这些吗？

Answer 1

我建议您按照OOP概念创建一个Player对象而不是许多实例变量，每个属性一个。所以，而不是

@player_1_hand
@player_3_value

尝试使用Player类

class Player
  attr_accessor :number, :hand, :value
  def initialize(number)
    @number = number
  end
end

然后

p1 = Player.new(1)
p2 = Player.new(2)
p3 = Player.new(3)
p4 = Player.new(4)
[p1,p2,p3,p4].each do |player|
  player.hand = ...
  player.value = ...
end


p1.hand #=> ...
p1.value #=> ...

Answer 2

我想警告你，我要给你的答案将适用于你想要完成的任务，但是你的方式类似于你需要锤子时使用扳手。当然，扳手可能会起作用，但我会解雇任何没有使用合适工具的水管工。

players.each { |p| puts instance_variable_get("@player_#{p}_hand") }

有关instance_variable_get的更多信息，请访问apidock。

一般情况下，除非是creating instances of a class，否则应远离实例变量。但是对于像这样的脚本，坚持使用普通变量并远离实例变量。

Answer 3

players = [1, 2, 3, 4]

players.each { |player|
instance_variable_set("@player_#{player}_hand", "foo")
instance_variable_set("@player_#{player}_value", "bar")
}

要调用您的变量，请使用eval

players.each { |player| 
puts instance_variable_get("@player_#{player}_hand") 
puts instance_variable_get("@player_#{player}_value")
}

要更新变量，请再次使用instance_variable_set

players.each { |player| 
instance_variable_set("@player_#{player}_hand", instance_variable_get("@player_#{player}_hand") + (player + 5).to_s)
puts instance_variable_get("@player_#{player}_hand")
}

所有打印：

foo
bar
foo
bar
foo
bar
foo
bar
foo6
foo7
foo8
foo9

Answer 4

当你想要每个属性的attr_accessor时，一个Struct而不是一个类会自动为你创建它们。

Player = Struct.new(:number, :hand, :value)

players = Array.new

(1..4).each do |i|
  player = Player.new(i)
  player.hand = 'something'
  player.value = 'blah'
  players.push player
end

players.each do |player|
  puts "Player #{player.number} has hand #{player.hand} with value #{player.value}"
end

输出：

Player 1 has hand something with value blah
Player 2 has hand something with value blah
Player 3 has hand something with value blah
Player 4 has hand something with value blah

如何在ruby

4 个答案: