[Nuby] Object ID Lookup?

[Jim Moy]

Hi all, a Ruby Nuby here with a question.

Is there a way to lookup an object reference from the object's id?
Something to do like the following, but without the need for the lookup
hash:

a = { "a" => 1, "b" => 2 }
b = { "c" => 4, "d" => 3 }
arr = [a, b]
ids = arr.collect {|h| h.id}
lookup = {}
arr.each { |h| lookup[h.id] = h }
cmp = ids.collect {|id| lookup[id]}
ids == cmp => true

In my instance, I've got a reference set of hashes that I'm pointing to
from multiple arrays. Those arrays are manipulated depending on sorting
and other factors.

I don't want to get Hash#== involved so I'm using the Hash object id's.
After processing is completed, I'd like to get back from the IDs to the
object references. The lookup is working, but I was wondering if there
was a better method.

Thanks for any suggestions,

Jim Moy
Fort Collins, Colorado
USA

 

[Joel VanderWerf]

Is there a way to lookup an object reference from the object's id?

You can use ObjectSpace._id2ref(x.id) to get a reference to x.

 

[Jim Moy]

You can use ObjectSpace._id2ref(x.id) to get a reference to x.

Thanks for the answer. My Ruby in a Nutshell says this is an "internal
use only" method, is that still the case as of 1.8?

Jim

 

[Yukihiro Matsumoto]

Hi,

In message "Re: [Nuby] Object ID Lookup?"

|> You can use ObjectSpace._id2ref(x.id) to get a reference to x.
|
|Thanks for the answer. My Ruby in a Nutshell says this is an "internal
|use only" method, is that still the case as of 1.8?

I don't recommend you to use it too often, because it's difficult to
use it right. The referencing object may be recycled by GC.

matz.

 

[Eric Hodel]

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Hi all, a Ruby Nuby here with a question.
=20
Is there a way to lookup an object reference from the object's id?=20
Something to do like the following, but without the need for the lookup
hash:
=20
a =3D { "a" =3D> 1, "b" =3D> 2 }
b =3D { "c" =3D> 4, "d" =3D> 3 }
arr =3D [a, b]
ids =3D arr.collect {|h| h.id}
lookup =3D {}
arr.each { |h| lookup[h.id] =3D h }
cmp =3D ids.collect {|id| lookup[id]}
ids =3D=3D cmp =3D> true
=20
In my instance, I've got a reference set of hashes that I'm pointing to
from multiple arrays. Those arrays are manipulated depending on sorting
and other factors.
=20
I don't want to get Hash#=3D=3D involved so I'm using the Hash object id'= s.=20
After processing is completed, I'd like to get back from the IDs to the
object references. The lookup is working, but I was wondering if there
was a better method.

Not seeing the internals of your code, will Object#equal? (identical
object ids) be able to replace #=3D=3D?

--=20
Eric Hodel - (e-mail address removed) - http://segment7.net
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[Jim Moy]

a = { "a" => 1, "b" => 2 }

b = { "c" => 4, "d" => 3 }
arr = [a, b]
ids = arr.collect {|h| h.id}
lookup = {}
arr.each { |h| lookup[h.id] = h }
cmp = ids.collect {|id| lookup[id]}
ids == cmp => true

In my instance, I've got a reference set of hashes that I'm
pointing to from multiple arrays. Those arrays are manipulated
depending on sorting and other factors.

I don't want to get Hash#== involved so I'm using the Hash
object id's. After processing is completed, I'd like to get
back from the IDs to the object references. The lookup is
working, but I was wondering if there was a better method.

Eric Hodel ([email protected]) wrote:

Not seeing the internals of your code, will Object#equal? (identical
object ids) be able to replace #==?

Yes, the code similar to the above example works as-is with the
hash ids, as I wanted to avoid Hash#== and all the comparisons it
will perform. Judging by the replies so far, I think I'll keep
the lookup hash.

Jim