[ruby-core:46417] [ruby-trunk - Bug #5406] inconsistent odd-length array rejection in Hash[*ary] vs Hash[ary]

Issue #5406 has been updated by matz (Yukihiro Matsumoto).

Assignee changed from matz (Yukihiro Matsumoto) to nobu (Nobuyoshi Nakada)

Hash[](ary) should raise an exception, when invalid input comes.

Matz.

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Bug #5406: inconsistent odd-length array rejection in Hash[*ary] vs Hash[ary]
https://bugs.ruby-lang.org/issues/5406#change-28039

Author: sunaku (Suraj Kurapati)
Status: Assigned
Priority: Normal
Assignee: nobu (Nobuyoshi Nakada)
Category: core
Target version: 2.0.0
ruby -v: ruby 1.9.2p290 (2011-07-09 revision 32553) [x86_64-linux]


Hello,

Hash[*ary] raises an error when given odd number of arguments:

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

In contrast, Hash[ary] silently accepts odd-length arrays:

>> Hash.[](  [1, 2, 3]  )
{}
>> Hash.[](  [[1, 2], 3]  )
{
    1 => 2
}
>> Hash.[](  [[1, 2], [3]]  )
{
    1 => 2,
    3 => nil
}
>> Hash.[](  [[1, 2], [3,4,5]]  )
{
    1 => 2
}

I think this behavior is inconsistent.  Please either:

(1) change Hash[ary] to raise errors upon seeing odd-length arrays or 

(2) change Hash[*ary] to not raise an error for odd number of arguments and instead accept the last odd argument as a key with value nil, just like this existing behavior:

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

Thanks for your consideration.


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