From: Nathan Broadbent <nathan.f77@...>
Date: 2012-11-08T05:00:25+09:00
Subject: [ruby-core:49064] [ruby-trunk - Feature #7297][Open] map_to alias for each_with_object

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> So consider Enumerable#associate which builds a mapping by *associating*
keys with values

I like Enumerable#associate. It would cover many of the cases where
each_with_object({}) is currently used.

However, I think '[[1,2],[3,4]].to_h' would be better for when an Array is
already in the 'associated' form. See #7292 for that discussion:
https://bugs.ruby-lang.org/issues/7292<https://bugs.ruby-lang.org/issues/7292#change-32586>
.

If the #to_h method was also available, then #associate could require a
block, and it would be the inverse of Active Support's 'index_by' method
(it would yields values instead of keys):
http://api.rubyonrails.org/classes/Enumerable.html#method-i-index_by

I'm still wondering if there should be a method that allows you to return
both key and value, but  'map {|e| [e * 2, e ** 2] }.to_h' would probably
be sufficient.

(sorry for bringing #7292 into the discussion, but I feel like it's a
related issue.)

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&gt;=A0<span>So consider Enumerable#associate which builds a mapping by *as=
sociating* keys with values</span><div><span><br></span></div><div><span>I =
like Enumerable#associate. It would cover many of the cases where each_with=
_object({}) is currently used.</span></div>


<div><span><br></span></div><div>However, I think &#39;[[1,2],[3,4]].to_h&#=
39; would be better for when an Array is already in the &#39;associated&#39=
; form. See #7292 for that discussion:=A0<span class=3D"Apple-style-span" s=
tyle=3D"line-height:normal"><a href=3D"https://bugs.ruby-lang.org/issues/72=
92#change-32586" target=3D"_blank" style=3D"color:rgb(17,85,204);text-decor=
ation:none">https://bugs.ruby-lang.org/<span></span>issues/7292</a>.</span>=
</div>
<div><br></div><div dir=3D"ltr">If the #to_h method was also available, the=
n #associate could require a block, and it would be<span class=3D"Apple-sty=
le-span" style><span>=A0the inverse of Active Support&#39;s &#39;index_by&#=
39; method (it would yields values instead of keys):=A0<span></span></span>=
<span><a href=3D"http://api.rubyonrails.org/classes/Enumerable.html#method-=
i-index_by" target=3D"_blank" style=3D"color:rgb(17,85,204);text-decoration=
:none">http://api.rubyonrails.org/classes/Enumerable.html#method-i-index_by=
</a></span></span></div>
<div><br></div><div dir=3D"ltr">I&#39;m still wondering if there should be =
a method that allows you to return both key and value, but=A0<span class=3D=
"Apple-style-span" style><span class=3D"Apple-style-span" style=3D"line-hei=
ght:normal">=A0&#39;</span><span class=3D"Apple-style-span" style>map {|e| =
[e * 2, e ** 2] }.to_h&#39; would probably be sufficient.=A0</span></span><=
/div>
<div dir=3D"ltr"><span class=3D"Apple-style-span" style><span class=3D"Appl=
e-style-span" style><br></span></span></div><div dir=3D"ltr"><span class=3D=
"Apple-style-span" style><span class=3D"Apple-style-span" style>(sorry for =
bringing #7292 into the discussion, but I feel like it&#39;s a related issu=
e.)<span></span></span></span></div>
<div><br></div><div><div><div><blockquote class=3D"gmail_quote" style=3D"ma=
rgin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex" dir=3D"ltr">

</blockquote></div></div></div>

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