Notification of object destruction in Ruby

Question

I have written a custom Rails model. This model is backed by an actually server not by a database table (so it does not inherit from ActiveRecord::Base). In o

Answer 1

If you need to control what happens when an object is destroyed, you really should be explicitly destroying it yourself - this is by design. You're not supposed to be able to destroy an object explicitly either - this is also by design.

In other words, from the perspective of your program, an object is never destroyed or destroyable. For these reasons you should re-think the problem (this is not an uncommon need - release of resources when the object is no longer needed) so it fits into the Ruby paradigm.

Setting the object to nil gives a hint to the garbage collector, but does not necessarily immediately destroy it.

However, if you must have the garbage collector handle it, then read on.

There is no direct support for a destructor, but you can have it call a finalizer function when it is destroyed.

According to http://pleac.sourceforge.net/pleac_ruby/classesetc.html it may not be garbage collected if it contains a reference to the original object, so must be a class method and not an instance method.

class MyClass
    def initialize
        ObjectSpace.define_finalizer(self,
                                     self.class.method(:finalize).to_proc)
    end
    def MyClass.finalize(id)
        puts "Object #{id} dying at #{Time.new}"
    end
end