Keep track of all instances of a class without losing GC?

Ruby
1

Hi,

I want to be able to keep track of all instances of a class using
something simple like this:

Class Thing
@@allthings = []

def initialize
    @@allthings.push self
end

end

However an obvious drawback to this approach is that instances of this
class will never be garbage collected due to the reference held in
@@allthings.

Is there a way to make it so this reference in @@allthings “doesn’t
count”, so to speak?

Or is there a better way of doing it?

Thanks for your help

2

On Sun, 27 Aug 2006, Jez S. wrote:

end

Thanks for your help

require ‘weakref’

check out the docs.

-a

3

On Sun, 27 Aug 2006 23:45:34 +0900, Jez S. wrote:

end

Thanks for your help

Have a look at weakref.rb. Either use that directly, or copy ideas from
weakref.rb to create your own system.

–Ken B.

4

On 8/27/06, Jez S. [email protected] wrote:

However an obvious drawback to this approach is that instances of this
class will never be garbage collected due to the reference held in
@@allthings.

Is there a way to make it so this reference in @@allthings “doesn’t
count”, so to speak?

Or is there a better way of doing it?

ObjectSpace already does it for you:
ObjectSpace.each_object(Thing) {|x| print x}

You could also use weak references, but Object Space is
much easier most of the time.

5

On 27-aug-2006, at 16:45, Jez S. wrote:

I want to be able to keep track of all instances of a class using
something simple like this:

Class Thing
@@allthings = []

def initialize
    @@allthings.push self
end

end

weakref might be of help indeed, you also can use lookups (3 extra
lines):

class Thing
@@things = []
def self.things
@@things.map{ | id | ObjectSpace._id2ref(id) }
end

 def initialize
     @@things << self.object_id
 end

end

After that you might get lost references when object get garbage
collected, but if you don’t need that - what’s the point ? :slight_smile: