Issue #6373 has been updated by phluid61 (Matthew Kerwin).


charliesome (Charlie Somerville) wrote:
> I think out of all the options proposed, 'identity' is the most readable/quickly understandable.
> 
> For example, I think the use of 'identity' reads very nicely in [1,2,3,4].group_by(&:identity)

Except that #identity seems to imply the same thing as #__id__ , and "a".__id__ is not necessarily == "a".__id__ , as Matz said earlier.

The advantage of using #reference is that there's no existing method or concept we're overloading;  there are no such things as "reference" objects (or "pointers") in Ruby -- it is understood that all references are automagically dereferenced when operated on -- so returning the references and then comparing them should be understood by most rubyists as effectively the same as comparing the objects directly (whatever "directly" means).

tl;dr:
Defining #identity that conflicts with #__id__ is confusing, however slightly it might be.
----------------------------------------
Feature #6373: public #self
https://bugs.ruby-lang.org/issues/6373#change-40109

Author: trans (SYSTEM ERROR)
Status: Feedback
Priority: Normal
Assignee: matz (Yukihiro Matsumoto)
Category: core
Target version: next minor


=begin
This was recently suggested to me as an extension:

  class Object
    # An identity method that provides access to an object's 'self'.
    #
    # Example:
    #   [1,2,3,4,5,1,2,2,3].group_by(&:identity)
    #   #=> {1=>[1, 1], 2=>[2, 2, 2], 3=>[3, 3], 4=>[4], 5=>[5]}
    #
    def identity
      self
    end
  end

First, is such a method commonly useful enough to warrant existence?

Second, it makes me wonder if #self should be a public method in general.
=end


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