将使用开放类的实例方法添加到 ruby​​ 中的 Object 类？

Question

我有一个类Operator，它执行其他对象的某些实例的代码块：

class Operator

    def operation(&block)
        #execution of a block in some object
    end
end

另一方面，我有 Criature 类

class Criature

    operational

    def level_up
        @level+=1
    end

end

我需要用公开课对Object 进行monkeypatch。

所以，我需要在 Object 中定义方法 operational ，因为每次 Operator 的实例执行 operation 时，（例如）块：{ c.level_up() } 将被执行在其类主体中带有operational 的每个实例。

我该怎么做？

Answer 1

执行一些对象的一些实例的代码块：

如果我很好理解，用方法

    operational

如果您想在 Criature 等某些类的主体中执行，您想标记它们的实例，并说“嘿，在执行 operation 时给我一个电话。”

来自The Pickaxe：

ObjectSpace.each_object(‹ class_or_mod›)

为这个 Ruby 进程中的每个活的、非立即的对象调用一次块。如果指定了 class_or_mod，则只为与 class_or_mod 匹配（或者是其子类）的类或模块调用块。

使用ObjectSpace 可以迭代某个类的对象。这给了我一个想法，签名，你想给某些实例的这个标志，可以用一个超类来完成。

ObjectSpace.each_object(Operational)

将收集具有此“签名”的类的所有实例。

文件tc.rb：

class Operational
    
end

class Criature < Operational
    def initialize(p_name)
        @name  = p_name
        @level = 0
    end
        
    def level_up
        @level+=1
        puts "level is now #{@level}"
    end
end

class XYZ < Operational
    def initialize(p_name)
        @name = p_name
    end
    
end

文件to.rb：

require_relative 'tc'

class Operator

    def operation(&block)
        #execution of a block in some object
        Special.currently_operational.each do | obj |
            puts "operation on #{obj.inspect}"
            block.call(obj) if obj.respond_to? 'level_up'
        end
    end
end

class Special
    def self.currently_operational
        operationals = []

        ObjectSpace.each_object(Operational) do | object |
            operationals << object
        end

        puts "#{operationals.size} objects are flagged as operational"
        operationals
    end
end

Criature.new('c1')
Criature.new('c2')
Criature.new('c3')

block = Proc.new{ | x | x.level_up }
puts 'first round'
Operator.new.operation(&block)

# later ...
XYZ.new('x1')
XYZ.new('x2')

puts 'second round'
Operator.new.operation(&block)

执行：

$ ruby -w to.rb 
first round
3 objects are flagged as operational
operation on #<Criature:0x007fc45683d2f0 @name="c3", @level=0>
level is now 1
operation on #<Criature:0x007fc45683d368 @name="c2", @level=0>
level is now 1
operation on #<Criature:0x007fc45683d3b8 @name="c1", @level=0>
level is now 1
second round
5 objects are flagged as operational
operation on #<XYZ:0x007fc45683cad0 @name="x2">
operation on #<XYZ:0x007fc45683cb48 @name="x1">
operation on #<Criature:0x007fc45683d2f0 @name="c3", @level=1>
level is now 2
operation on #<Criature:0x007fc45683d368 @name="c2", @level=1>
level is now 2
operation on #<Criature:0x007fc45683d3b8 @name="c1", @level=1>
level is now 2