Question

我正在尝试从循环内初始化一个类的实例，并且我不确定如何命名该对象，以便每次迭代都有一个新名称，因此我没有调用五个对象/实例'my_animal'？

my_array = ["Fluffy", "Lala", "Jo", "Cersei", "Berlin"]
my_array.each do |e|
    my_animal = Animal.new(e)
end


class Animal
attr_accessor :name
    def initialize (name)
        @name = name
    end


end

Answer 1

你可以这样做：

my_array = ["Fluffy", "Lala", "Jo", "Cersei", "Berlin", "Jo"]
arr = my_array.each_with_index.with_object([]) do |(e,i),a|
    a << Animal.send(:new, "#{e}#{i}")        
end
  #=> [#<Animal:0x007fe3e4087b20 @name="Fluffy0">,
  #    #<Animal:0x007fe3e4087a80 @name="Lala1">,
  #    #<Animal:0x007fe3e40879e0 @name="Jo2">,
  #    #<Animal:0x007fe3e4087940 @name="Cersei3">,
  #    #<Animal:0x007fe3e4087878 @name="Berlin4">,
  #    #<Animal:0x007fe3e31d5618 @name="Jo5">] 

arr.map(&:name)
  #=> ["Fluffy0", "Lala1", "Jo2", "Cersei3", "Berlin4", "Jo5"]

或者，以下方式传达了其他信息：

my_array = ["Fluffy", "Lala", "Jo", "Cersei", "Lala", "Jo", "Berlin", "Jo"]
arr = my_array.each_with_object([]) do |s,a|
  instance = a.reverse.find { |i| i.name =~ /^#{s}/ }
  if instance
    old_name = instance.name
     prefix, nbr = old_name.split(/(\d+)/)
    new_name = "#{prefix}#{((nbr.to_i)+1).to_s}"
  else 
    new_name = "#{s}0"
  end        
  a << Animal.send(:new, new_name)        
end
  #=> [#<Animal:0x007fe3e402e458 @name="Fluffy0">,
  #    #<Animal:0x007fe3e402e1b0 @name="Lala0">,
  #    #<Animal:0x007fe3e402dc38 @name="Jo0">,
  #    #<Animal:0x007fe3e402d120 @name="Cersei0">,
  #    #<Animal:0x007fe3e402c540 @name="Lala1">,
  #    #<Animal:0x007fe3e4097d68 @name="Jo1">,
  #    #<Animal:0x007fe3e4096d00 @name="Berlin0">,
  #    #<Animal:0x007fe3e4096698 @name="Jo2">] 
arr.map(&:name)
  #=> ["Fluffy0", "Lala0", "Jo0", "Cersei0", "Lala1", "Jo1", "Berlin0", "Jo2"]

Answer 2

将所有新对象推送到数组而不是静态变量，然后您可以用数字方式访问它们。

Answer 3

您可以尝试将它们放入哈希，然后您可以像my_animals["Lala"]一样访问它们。

class Animal
  attr_accessor :name
  def initialize (name)
    @name = name
  end
end

my_array = ["Fluffy", "Lala", "Jo", "Cersei", "Berlin"]
my_animals = Hash.new

my_array.each do |e|
  my_animals[e] = Animal.new(e)
end

Answer 4

您的代码发生了什么，以及您在my_animal = Animal.new(e)上创建的每个实例都丢失了。你必须在某些结构上跟踪所有这些。像字典（哈希）或数组。

这可能会有所帮助：

class Animal
    attr_accessor :name

    def initialize (name)
        @name = name
    end
end

my_array = ["Fluffy", "Lala", "Jo", "Cersei", "Berlin"]

my_instances = {}

my_array.each do |e|
    my_animal = Animal.new(e)

    my_instances[e] = my_animal
end

现在您有一个带有对象的数组的名称（字符串）。它将类似于：

my_instance = { "Fluffy" => #<Animal:0x0000000280d638 @name="Fluffy">,
                "Lala"   => #<Animal:0x0000000280d5e8 @name="Lala">,
                "Jo"     => #<Animal:0x0000000280d598 @name="Jo">,
                "Cersei" => #<Animal:0x0000000280d548 @name="Cersei">,
                "Berlin" => #<Animal:0x0000000280d4f8 @name="Berlin">
              }

如何从Ruby中的循环创建类的实例？

4 个答案: