Issue #9239 has been updated by marcandre (Marc-Andre Lafortune).


One reason I think I was wrong is that current form could encourage code like:

  enum.map{|x| [x.foo, x.bar] if x.baz? }.to_h

using the fact that any `nil` will be ignored. I'm not sure that it's a good idea.

It would probably be safer to raise an Exception for elements that are not a key-value pair. It also satisfies fail-early principle.

Matz, what do you think?
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Feature #9239: Array#to_h ignores flat arrays
https://bugs.ruby-lang.org/issues/9239#change-43681

Author: sawa (Tsuyoshi Sawada)
Status: Open
Priority: Normal
Assignee: matz (Yukihiro Matsumoto)
Category: 
Target version: 


=begin
My understanding was that the newly introduced `Array#to_h` was to be equivalent to `Hash.[]`. But when I give a flat array, it returns an empty hash:

    [:a, :b].to_h # => {}
    [:a].to_h     # => {}

I expected `{:a => :b}` for the first example, and `ArgumentError: odd number of arguments for Hash` for the second example, as is with `Hash[]`. Was it intended to be different? If so, why is that the case? Even if it is to be different, it should at least raise an error when a flat array is given.
=end



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