Ruby method Array#<< not updating the array in hash
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by Mladen Jablanovic
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Published on 2010-03-31T11:49:50Z
Indexed on
2010/03/31
11:53 UTC
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Inspired by http://stackoverflow.com/questions/2552363/how-can-i-marshal-a-hash-with-arrays I wonder what's the reason that Array#<< won't work properly in the following code:
h = Hash.new{Array.new}
#=> {}
h[0]
#=> []
h[0] << 'a'
#=> ["a"]
h[0]
#=> [] # why?!
h[0] += ['a']
#=> ["a"]
h[0]
#=> ["a"] # as expected
Does it have to do with the fact that << changes the array in-place, while Array#+ creates a new instance?
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