From: "MartinBosslet (Martin Bosslet)" <Martin.Bosslet@...>
Date: 2012-03-29T06:40:55+09:00
Subject: [ruby-core:43819] [ruby-trunk - Feature #6219] Return value of Hash#store


Issue #6219 has been updated by MartinBosslet (Martin Bosslet).


Right, good point. OK, then let me rephrase it for explicitly calling store. What I would prefer is:

h = { a: 1 }
h.store(:a, 2) # => 1
h.store(:b, 3) # => nil

That way I can check for collisions in one pass without having to call has_key? first. Otherwise
the result is evaluating the internal hash function twice, once for has_key? and once for the 
following call to store.
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Feature #6219: Return value of Hash#store
https://bugs.ruby-lang.org/issues/6219#change-25323

Author: MartinBosslet (Martin Bosslet)
Status: Open
Priority: Low
Assignee: 
Category: core
Target version: 


Hash#store returns the value that was just assigned, for example:

  h[:a] = b # => b

Does anyone rely on this behavior, are there cases when this becomes handy?

If however the return value is discarded most of the time, I was thinking it 
might be beneficial if we would return the previous value of a given key (nil if
none was assigned yet) instead. That way we could assign and check for a collision
in one pass, something that right now can only be done in two separate steps.




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