From: "marcandre (Marc-Andre Lafortune)" <ruby-core@...>
Date: 2013-08-31T07:38:29+09:00
Subject: [ruby-core:56893] [ruby-trunk - Feature #7292][Open] Enumerable#to_h


Issue #7292 has been updated by marcandre (Marc-Andre Lafortune).

File to_h.pdf added
Status changed from Feedback to Open

matz (Yukihiro Matsumoto) wrote:
> But I am not sure the following simple implementation works OK, e.g. what if an element is a object, or number, or anything not two-element array.

Agreed.

I believe we should only treat elements that are array-like and of length 2. More explicitly, either the Enumerable yields one value that responds_to?(:to_ary) and returns a 2-element array, or the Enumerable yields exactly two values. Other cases should be ignored, in the same way that String#to_i ignores invalid characters.

Slide attached.

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Feature #7292: Enumerable#to_h
https://bugs.ruby-lang.org/issues/7292#change-41441

Author: marcandre (Marc-Andre Lafortune)
Status: Open
Priority: Low
Assignee: matz (Yukihiro Matsumoto)
Category: core
Target version: next minor


Now that #to_h is the official method for explicit conversion to Hash, we should also add

	Enumerable#to_h: Returns a hash for the yielded key-value pairs.

	  [[:name, 'Joe Smith'], [:age, 42]].to_h # => {name: 'Joe Smith', age: 42}


With the Ruby tradition of succint documentation I suggest the documentation talk about key-value pairs and there is no need to be explicit about the uninteresting cases like:

    (1..3).to_h           # => {1 => nil, 2 => nil, 3 => nil}
    [[1, 2], [1, 3]].to_h # => {1 => 3}
    [[1, 2], []].to_h     # => {1 => 2, nil => nil}

I see some reactions of people reading about the upcoming 2.0 release like this one:
http://globaldev.co.uk/2012/11/ruby-2-0-0-preview-features/#dsq-comment-body-700242476



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