Feature #5805: object_hexid

• Status: Feedback
• Assignee: -
• Target version: -

[trans (Thomas Sawyer)]

I would like to see #object_hexid added to Ruby to return an object's id in hexidecimal form.

By default Ruby will show this id when using #inspect.

Object.new.inspect
=> "#Object:0x000000023cadf0"

I, for one, have often wanted to include this hex id when I customize an #inspect method for a class. But despite my lengthy efforts I have never been able to ensure the hex id is correct. It seems to vary a great deal depending on platform and Ruby version.

You can see the current effort at this here: https://github.com/rubyworks/facets/blob/master/lib/core/facets/kernel/object_hexid.rb But this definition is currently failing on Ruby 1.8.7 and JRuby. I have tried a number of variations, but nothing sees to work for all platforms.

My last ditch approach will be to bind Kernel#inspect InstanceMethod to the current object and extract the hex id from it's output. It should work, but it's definitely a hack. In the future I'd much rather just ask Ruby for it!

[shevegen (Robert A. Heiler)]

I think this seems like a simple proposal.

[nobu (Nobuyoshi Nakada)]

• Status changed from Open to Feedback

Hi,

(11/12/25 0:22), Thomas Sawyer wrote:

By default Ruby will show this id when using #inspect.

  Object.new.inspect
  => "#<Object:0x000000023cadf0>"

I, for one, have often wanted to include this hex id when I customize an #inspect method for a class. But despite my lengthy efforts I have never been able to ensure the hex id is correct. It seems to vary a great deal depending on platform and Ruby version.

In 1.9.3 or later

  module Kernel
    def object_hexid
      "0x"+[object_id<<1].pack("L>!").unpack("H*")[0]
    end
  end

You can see the current effort at this here: https://github.com/rubyworks/facets/blob/master/lib/core/facets/kernel/object_hexid.rb But this definition is currently failing on Ruby 1.8.7 and JRuby. I have tried a number of variations, but nothing sees to work for all platforms.

Even if the method were added, it would never affect 1.9 or earlier, so it changes nothing for 1.8.7.
Is the target of your library only 2.0 or later?

[shyouhei (Shyouhei Urabe)]

On 2011年12月25日 14:38, Nobuyoshi Nakada wrote:

In 1.9.3 or later

  module Kernel
    def object_hexid
      "0x"+[object_id<<1].pack("L>!").unpack("H*")[0]
    end
  end

I prefer to use sprintf() instead.

[trans (Thomas Sawyer)]

Thank you for 1.9.3+ definition, I will add that. Do you happen to know definition for 1.8.7? I am not worried about anything older than that.

Even if the method were added, it would never affect 1.9 or earlier, so it changes nothing for 1.8.7. Is the target of your library only 2.0 or later?

That's true. But if the definition should ever change again, this issue will come up again. So I think still better that Ruby make it's definition accessible.

[trans (Thomas Sawyer)]

On 2011年12月25日 14:38, Nobuyoshi Nakada wrote:

In 1.9.3 or later

  module Kernel
    def object_hexid
      "0x"+[object_id<<1].pack("L>!").unpack("H*")[0]
    end
  end

Hmm.. this seems to pad two extra zeros.

"0x00000000014100e0"

instead of

"0x000000014100e0"

Is Urabe correct? Does sprintf work just as well? I don't know #pack and Ruby internals enough to be sure.

Also, here is 1.8.7 test failure.

(assertion) a == b
a) "#<Object:0x..fb710eb4c>"
b) "#<Object:0xb710eb4c>"
    test_object_hexid.rb:9
    07     test do
    08       o = Object.new
 => 09       "#<Object:#{o.object_hexid}>".assert == o.inspect
    10     end

[nobu (Nobuyoshi Nakada)]

My last ditch approach will be to bind Kernel#inspect InstanceMethod to the current object and extract the hex id from it's output. It should work, but it's definitely a hack. In the future I'd much rather just ask Ruby for it!

You can use super.

[trans (Thomas Sawyer)]

Sorry, how does super help?

[now (Nikolai Weibull)]

On Sun, Jan 8, 2012 at 17:33, Thomas Sawyer [e-mail] wrote:

Sorry, how does super help?

   def inspect
     '#<IWhoNeedAHexID: %s>' % super.sub(/\A.*(0x[0-9a-f]+).*/, '\\1')
   end

perhaps?

[mame (Yusuke Endoh)]

• Target version set to 2.6

[naruse (Yui NARUSE)]

• Target version deleted (2.6)