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* [ruby-core:100200] [Ruby master Misc#17199] id outputed by inspect and to_s output does not allow to find actual object_id and vice-versa
@ 2020-09-28 11:40 baptiste.courtois
  2020-10-20 15:55 ` [ruby-core:100446] " chris
                   ` (5 more replies)
  0 siblings, 6 replies; 7+ messages in thread
From: baptiste.courtois @ 2020-09-28 11:40 UTC (permalink / raw)
  To: ruby-core

Issue #17199 has been reported by Annih (Baptiste Courtois).

----------------------------------------
Misc #17199: id outputed by inspect and to_s output does not allow to find actual object_id and vice-versa
https://bugs.ruby-lang.org/issues/17199

* Author: Annih (Baptiste Courtois)
* Status: Open
* Priority: Normal
----------------------------------------
Hello, here is my first ruby issue sorry in advance if it is incorrectly filled.

# Issue

The value returned by `#object_id` is not aligned anymore with displayed info in `#inspect` and `#to_s` methods.

## with ruby < 2.7

``` ruby
Object.new.tap { |o| p "#to_s=#{o.to_s}, #inspect=#{o.inspect}, #__id__=#{o.__id__}, shifted_id=#{(o.__id__ << 1).to_s(16)}" }
"#to_s=#<Object:0x0000000000d202a8>, #inspect=#<Object:0x0000000000d202a8>, #__id__=6881620, shifted_id=d202a8"
```

## with ruby >= 2.7

``` ruby
 Object.new.tap { |o| p "#to_s=#{o.to_s}, #inspect=#{o.inspect}, #__id__=#{o.__id__}, shifted_id=#{(o.__id__ << 1).to
s(16)}" }
"#to_s=#<Object:0x0000555dc8640b88>, #inspect=#<Object:0x0000555dc8640b88>, #__id__=220, shifted_id=1b8"
```


# Consequences

It makes harder:
- to implement a clean override of the `#inspect` method. i.e. How to keep the same output without ability to compute to the same "object_id" value.
- to debug the object using the inspect output. i.e. `ObjectSpace._id2ref(id_from_inspect >> 1)` used to work, now it doesn't (`RangeError: <xXx> is not id value`).

# Suggestion

IMHO either:
- the `#to_s` and `#inspect` documentation are obsolete `The default [...] [shows|prints] [...] an encoding of the object id` and the change could have been a bit more advertised
- they should use the result of `#object_id` instead of displaying the object pointer address

Another solution could be to provide a method to get access to the address, but I'm not sure you want that.

P.S. While debugging my problem I found [this ruby-forum thread](https://www.ruby-forum.com/t/understanding-object-id-in-ruby-2-7/260268/4) where people dived a bit more than me into ruby's code.



-- 
https://bugs.ruby-lang.org/

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-- links below jump to the message on this page --
2020-09-28 11:40 [ruby-core:100200] [Ruby master Misc#17199] id outputed by inspect and to_s output does not allow to find actual object_id and vice-versa baptiste.courtois
2020-10-20 15:55 ` [ruby-core:100446] " chris
2020-10-20 18:31 ` [ruby-core:100448] " johnson.joel.b
2020-10-20 20:06 ` [ruby-core:100450] " eregontp
2020-10-20 20:15 ` [ruby-core:100451] " nate.berkopec
2020-10-20 21:32 ` [ruby-core:100458] " tenderlove
2020-10-20 21:35 ` [ruby-core:100459] " tenderlove

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