[ruby-core:106049] [Ruby master Bug#18334] ENV#to_h returns a new Hash object but Hash#to_h does not, which can cause inconsistencies

Issue #18334 has been updated by Eregon (Benoit Daloze).


I think it would be confusing if `ENV#dup` returns a `Hash` and not a `ENV`, as that would be inconsistent with all other `#dup`.

`to_SHORT` never guarantees to return a copy, so if you don't know the receiver and want to mutate it, you should probably use `obj.to_h.dup`, which already works fine.

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Bug #18334: ENV#to_h returns a new Hash object but Hash#to_h does not, which can cause inconsistencies
https://bugs.ruby-lang.org/issues/18334#change-94636

* Author: postmodern (Hal Brodigan)
* Status: Open
* Priority: Normal
* ruby -v: ruby 3.1.0dev (2021-11-13T20:48:57Z master fc456adc6a) [x86_64-linux]
* Backport: 2.6: UNKNOWN, 2.7: UNKNOWN, 3.0: UNKNOWN
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I noticed that in ruby-3.1.0-preview1 ENV#dup was removed in favor of ENV#to_h. However, methods that accept either ENV or a Hash object will not behave the same, since ENV#to_h returns a new Hash object but Hash#to_h returns the same Hash instance.

    ENV.to_h.object_id
    # => 14700
    ENV.to_h.object_id
    # => 14760
    hash = {"FOO" => "bar"}
    hash.to_h.object_id
    # => 14820
    hash.to_h.object_id
    # => 14820

I propose that the ENV#dup method be re-added as `self.to_h.dup`.



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