Hash with indifferent access reverse merge problem
Reported by David Lowenfels | June 14th, 2008 @ 11:02 PM
My business partner Rodney ran into this isse the other day.
http://blog.internautdesign.com/...
I think it is a bug, that violates the Principle of Least Surprise.
Loading development environment (Rails 2.1.0)
>> z = HashWithIndifferentAccess.new
=> {}
>> z.reverse_merge!( :a => 1 )
=> {:a=>1}
>> z.reverse_merge!( 'a' => 1 )
=> {"a"=>1, :a=>1}
Reverse merging on a HashWithIndifferentAccess should return a new HashWithIndifferentAccess, not a normal hash.
The solution is to overload HashWithIndifferentAccess#reverse_merge:
>> class HashWithIndifferentAccess
>> def reverse_merge(other_hash)
>> self.class.new( other_hash.merge(self) )
>> end
>> end
=> nil
>> z = HashWithIndifferentAccess.new
=> {}
>> z.reverse_merge!( :a => 1 )
=> {"a"=>1}
>> z.reverse_merge!( 'a' => 1 )
=> {"a"=>1}
>>
I'm attaching a patch with a test.
Comments and changes to this ticket
-
DrMark June 25th, 2008 @ 09:14 PM
- → Tag changed from “” to “activesupport bug core_ext patch”
+1 This is rather unexpected behavior. Given that Ruby tries to do the least surprising thing, shouldn't we fix this?
-
Rodney Carvalho July 8th, 2008 @ 05:46 PM
+1 Yes, this caused me hours of frustration. Indifferent access should happen on both getting and setting.
-
Gregory Tomei July 22nd, 2008 @ 09:04 PM
this does seem to be inconsistent with how the HashWithIndifferentAccess class is intended to work.
-
H@rlan Knight July 22nd, 2008 @ 11:53 PM
+1 Agreed, this would be a serious improvement. The current behavior leads to difficult-to-trace bugs.
-
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