I don't think merge shoud be responsible for handling special cases like the array. You really should convert the array to a hash before. If you need to use such thing as reverse_merge!, why not use it like this: user_opts |= defaults being "|" an alias for anon destructive reverse_merge? I don't like havin "|" as a destructive operator. As for new operators, reverse_merge would be better represented as >>, but I don't think that's going to be approved. I'd still stick with << aliased to merge!, but | to reverse_merge is interesting as well. On Aug 17, 2013 4:32 PM, "alexeymuranov (Alexey Muranov)" < redmine / ruby-lang.org> wrote: > > Issue #8772 has been updated by alexeymuranov (Alexey Muranov). > > > trans (Thomas Sawyer) wrote: > > Actually I think #<< is good too. But it's definition needs to be a bit > more flexible than just merge. That's because it needs to do this: > > > > h = {} > > h << [:a,1] > > h << [:b,2] > > h #=> {:a=>1, :b=>2} > > Thomas, why h[:a] = 1, h[:b] = 2 wouldn't work for you? Or h << [[:a, 1], > [:b, 2]].to_h (#7292) ? > ---------------------------------------- > Feature #8772: Hash alias #| merge, and the case for Hash and Array > polymorphism > https://bugs.ruby-lang.org/issues/8772#change-41231 > > Author: trans (Thomas Sawyer) > Status: Open > Priority: Normal > Assignee: > Category: core > Target version: current: 2.1.0 > > > Ideally Hash and Array would be completely polymorphic in every manner in > which it is possible for them to be so. The reason for this is very simple. > It makes a programmer's life easier. For example, in a recent program I was > working on, I had a list of keyboard layouts. > > layouts = [layout1, layout2, layout3] > > Later I realized I wanted to identify them by a label not an index. So... > > layouts = {:foo => layout1, :bar => layout2, :baz => layout3} > > Unfortunately this broke my program in a number of places, and I had to go > through every use of `layouts` to translate what was an Array call into a > Hash call. If Array and and Hash were more polymorphic I would have only > had to adjust the places were I wanted to take advantage of the Hash. > Ideally almost nothing should have actually broken. > > The achieve optimal polymorphism between Hash and Array is to treat a > Hash's keys as indexes and its values as as the values of an array. e.g. > > a = [:a,:b,:c] > h = {0=>:a,1=>:b,2=>:c} > a.to_a #=> [:a,:b,:c] > h.to_a #=> [:a,:b,:c] > > Of course the ship has already sailed for some methods that are not > polymorphic, in particular #each. Nonetheless it would still be wise to try > to maximize the polymorphism going forward. (Perhaps even to be willing to > take a bold leap in Ruby 3.0 to break some backward compatibility to > improve upon this.) > > In the mean time, let us consider what it might mean for Hash#+ as an > alias for #merge, *if the above were so*: > > ([:a,:b] + [:c,:d]).to_a => [:a,:b,:c,:d] > ({0=>:a,1=>:b} + {2=>:c,3=>:d}).to_a => [:a,:b,:c,:d] > > ([:a,:b] + [:a,:b]).to_a => [:a,:b,:a,:b] > ({0=>:a,1=>:b} + {0=>:a,1=>:b}).to_a => [:a,:b] > > Damn! So it appears that #+ isn't the right operator. Let's try #| instead. > > ([:a,:b] | [:c,:d]).to_a => [:a,:b,:c,:d] > ({0=>:a,1=>:b} | {2=>:c,3=>:d}).to_a => [:a,:b,:c,:d] > > ([:a,:b] | [:a,:b]).to_a => [:a,:b] > ({0=>:a,1=>:b} | {0=>:a,1=>:b}).to_a => [:a,:b] > > Bingo. So I formally stand corrected. The best alias for merge is #| not > #+. > > Based on this line of reasoning I formally request the Hash#| be an alias > of Hash#merge. > > P.S. Albeit, given the current state of polymorphism between Ruby's Array > and Hash, and the fact that it will probably never be improved upon, I > doubt it really matters which operator is actually used. > > > > -- > http://bugs.ruby-lang.org/ >