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

[Jez Stephens]

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

 

[Ken Bloom]

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

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

--Ken Bloom

 

[ara.t.howard]

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

require 'weakref'

check out the docs.

-a

 

[Tomasz Wegrzanowski]

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?

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.

 

[Julian 'Julik' Tarkhanov]

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 ?