From: Suraj Kurapati <redmine@...>
Date: 2010-04-13T09:19:11+09:00
Subject: [ruby-core:29485] [Feature #3131] add Kernel#Hash() method like Kernel#Array()

Issue #3131 has been updated by Suraj Kurapati.


Hi,

Please allow me to clarify.

Suraj Kurapati wrote:
> Hash::[] does not support conversion from odd-length Array (because
> it is uncertain what Ruby must do with the 2n+1'th element) and will
> raise an error in such case.

I was referring to this particular behavior:

>> Hash[1,2,3,4,5,6]
=> {1=>2, 3=>4, 5=>6}

>> Hash[1,2,3,4,5,6,7]
ArgumentError: odd number of arguments for Hash
	from (irb):3:in `[]'
	from (irb):3
	from /usr/bin/irb:12:in `<main>'

I forgot that Hash::[] can convert Array of 2-element Array into Hash:

>> Hash[1,2,3,4,[5,6],[7]]            # non 2-element Array ignored
=> {1=>2, 3=>4, [5, 6]=>[7]}

>> Hash[[1,2,3,4,[5,6],[7]]]          # implicit pair value is nil
=> {5=>6, 7=>nil}

>> Hash[[1,2,3,4,[5,6],[7,8],[7]]]    # previous pair is overwritten
=> {5=>6, 7=>nil}

Thanks for your consideration.
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http://redmine.ruby-lang.org/issues/show/3131

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