在删除对象时运行方法 [英] Run a Method on deletion of an Object

问题描述

我正在学习 ruby​​ 并且还没有找到一种方法来覆盖等效的 object.delete 函数:

I am learning ruby and haven't found a way to override an equivalent object.delete function:

我是这样做的:

    class Foo
        @@no_foo=0
        def initialize
            @@no_foo+=1
        end
        def delete
            #class specific cleanup...
            @@no_foo-=1
        end
        def Foo.no_foo
            return "#@@no_foo"
        end
    end

    def delete(obj)
        #object independent cleanup...
        obj.delete
        return nil
    end

    foo1 = Foo.new
    foo2 = Foo.new

    puts Foo.no_foo

    puts foo2
    foo2 = delete(foo2)
    puts foo2

    puts Foo.no_foo

如您所见，这种处理方式有点古怪...有没有更简单的方法来解决这个问题?
基本上，我想让我的对象在减少该类的总计数器的同一个调用中无法访问.我找不到在将变量(指向对象的指针)设置为 nil 时调用的方法.

As you can see, this is a bit of a hacky way of going about things... is there an easier way to go about this?
Basically I would like to make my objects unaccessible in the same call as decrementing the total counter for that class. I couldn't find a method that gets called when setting a variable(pointer to object) to nil.

我发现无法删除对象.

推荐答案

根据@RubyLovely 提供的链接:WeakRef.
我整理了以下示例类:

as per the link provided by @RubyLovely: WeakRef.
I put together the following sample class:

require 'weakref'
  class Foo
    #block to excecute on GC.start...
    FINALIZER = lambda { |object_id| p "finalizing %d" % object_id; @@no_foo -=1 }

    @@no_foo=0
    def initialize
        @@no_foo+=1
        #Initialising the finalizer...
        ObjectSpace.define_finalizer(self, FINALIZER)
    end

    def Foo.no_foo
        @@no_foo
    end
end

foo = Foo.new
foo = WeakRef.new(foo)
puts Foo.no_foo

GC.start

puts Foo.no_foo

这篇关于在删除对象时运行方法的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！