From: Nathan Broadbent <nathan.f77@...>
Date: 2012-11-01T12:08:18+09:00
Subject: [ruby-core:48692] Re: [ruby-trunk - Feature #7241][Open] Enumerable#to_h proposal

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>
> Almost no one uses #each_with_object as it is. #each_with_hash is hardly
> better. We need a short method name. Moreover I don't think this method's
> behavior is really the best approach to the real use case.
>

It's true that each_with_object doesn't seem to be used too much, but when
it is used, the object is usually a hash (for 90% of the cases in Rails, at
least.)

I think that each_with_hash should be provided for when you want to map an
enumerable onto a Hash, but I think that there should also be a 'to_h'
method on Array for when you just want to *convert* an Array into a hash.

I think 'to_h' would be most useful if it supported the behaviour of both
`Hash[ arr ]`, and 'Hash[ *arr ]'. I'm on my phone at the moment, but
here's how I could see that working:

def to_h
  if self.all? {|el| el.respond_to? :each && el.size == 2 }
    Hash[self]
  else
    Hash[*self]
  end
end

We could just let Hash[] handle any invalid input.

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<blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1p=
x #ccc solid;padding-left:1ex">Almost no one uses #each_with_object as it i=
s. #each_with_hash is hardly better. We need a short method name. Moreover =
I don&#39;t think this method&#39;s behavior is really the best approach to=
 the real use case.<div class=3D"gmail_extra">

</div>
</blockquote><div><br></div><div>It&#39;s true that each_with_object doesn&=
#39;t seem to be used too much, but when it is used, the object is usually =
a hash (for 90% of the cases in Rails, at least.)</div><div><br></div>
<div>I think that each_with_hash should be provided for when you want to ma=
p an enumerable onto a Hash, but I think that there should also be a &#39;t=
o_h&#39; method on Array for when you just want to *convert* an Array into =
a hash.=A0</div>
<div><br dir=3D"ltr"></div><span class=3D"Apple-style-span" style>I think &=
#39;to_h&#39; would be most useful if it supported the behaviour of both `H=
ash[ arr ]`, and &#39;Hash[ *arr ]&#39;.=A0</span><span class=3D"Apple-styl=
e-span" style>I&#39;m on my phone at the moment, but here&#39;s how I could=
 see that working:</span><div>
<br></div><div>def to_h</div><div>=A0 if self.all? {|el| el.respond_to? :ea=
ch &amp;&amp; el.size =3D=3D 2 }</div><div>=A0 =A0 Hash[self]</div><div>=A0=
 else</div><div>=A0 =A0 Hash[*self]</div><div>=A0 end</div><div>end</div><d=
iv><br></div><div>
We could just let Hash[] handle any invalid input.<span></span></div>

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