Created
February 22, 2013 17:32
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The truth behind Hash default value
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| # http://www.ruby-doc.org/core-1.9.3/Hash.html#method-c-new | |
| # ... It is the block’s responsibility to store the value in the hash if required. | |
| cuca = Hash.new([]) | |
| cuca["ola"] << 12 # ~ [] << 12 | |
| p cuca # => {} | |
| cuca = Hash.new([]) | |
| cuca["ola"] = cuca["ola"] << 12 | |
| p cuca # => {"ola"=>[12]} |
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When you use Hash.new() this means that will be returned instead of nil when accessing non-existing keys. But this WILL NOT associate the returned object as a value for the requested key. Simple enough, but leads to "i don't fucking know why this is'nt working" situations. It's one of those things that one expect ruby to do by itself.