在創建時收集數組中的類實例

Question

class Person 
    attr_accessor :name 

    def initialize(name) 
    @@name = name 
    people.push($) 
    end 
end 

它不必位於初始化函數中。我只想創建一個所有人員的數組。

p1 = Person.new("joe") 
p2 = Person.new("rick") 
people.inspect #-->would return [p1, p2] 

Answer 1

如果你只是想Person所有實例的列表，你不需要他們在創建補充。只需訪問他們：

ObjectSpace.each_object(Person).to_a 

Answer 2

@ sawa的回答是最好的，因爲它不會阻止垃圾回收。如果你要錄製爲它創建的每個實例（和防止否則，未使用的情況下，垃圾收集），你可以簡單地說：

class Person 
    @all = [] 
    def self.all; @all; end 
    attr_accessor :name 
    def initialize(name) 
    @name = name 
    self.class.all << self 
    end 
end 

p1 = Person.new("joe") 
p2 = Person.new("rick") 
p Person.all 
#=> [#<Person:0x007f9d1c8c4838 @name="joe">, 
#=> #<Person:0x007f9d1c8bb0d0 @name="rick">] 

Answer 3

我，強制性，將在這裏介紹my NameMagic：

# first, gem install y_support 
require 'y_support/name_magic' 

class Person 
    include NameMagic 
    # here, Person receives for free the following functionality: 
    # * ability to use :name (alias :ɴ) named argument in the constructor 
    # * #name (alias #ɴ) instance method 
    # * #name= naming/renaming method 
    # * ability to name anonymous instances by merely assigning to constants 
    # * collection of both named and anonymous instances inside the namespace 
    # * hooks to modify the name, or do something else when the name is assigned 
    # * ability to specify a different namespace than mother class for instance collection 
end 

Joe = Person.new #=> #<Person:0xb7ca89f8> 
Rick = Person.new #=> #<Person:0xb7ca57bc> 

Joe.name #=> :Joe 
Rick.ɴ #=> :Rick 
Person.instances # [#<Person:0xb7ca89f8>, #<Person:0xb7ca57bc>] 
Person.instance_names # [:Joe, :Rick] 

Person.new name: "Kit" #=> #<Person:0xb9776244> 
Person.instance_names #=> [:Joe, :Rick, :Kit] 
p3 = Person.instance(:Kit) #=> #<Person:0xb9776244> 
p2 = Person.instance("Rick") #=> #<Person:0xb7ca57bc> 
# Also works if the argument is already a Person instance: 
p1 = Person.instance(Person.instance(:Joe)) #=> #<Person:0xb9515ba8> 

anon = Person.new #=> #<Person:0xb9955c54> 
Person.instances.size #=> 4 
Person.instance_names #=> [:Joe, :Rick, :Kit] 
anon.name = :Hugo 
Person.instance_names #=> [:Joe, :Rick, :Kit, :Hugo] 
Person::Hugo #=> #<Person:0xb9955c54> 

有關垃圾回收的擔憂，一個可以忘記實例

Person.forget :Hugo #=> Returns, for the last time, "Hugo" instance 
Person::Hugo #=> NameError 
Person.forget_all_instances #=> [:Joe, :Rick, :Kit] 
Person.instances #=> [] - everything is free to be GCed 

引擎蓋下NameMagic使用相同的方法@sawa提議（至少在const_assigned鉤子由Ruby核心開發者提供）之前，即搜索整個ObjectSpace - 但不是針對母對象的實例，而是針對名稱空間（Module類對象），其常量被搜索到未命名的實例被分配給他們。