From: "nobu (Nobuyoshi Nakada)" Date: 2012-03-30T01:09:11+09:00 Subject: [ruby-core:43883] [ruby-trunk - Feature #6219] Return value of Hash#store Issue #6219 has been updated by nobu (Nobuyoshi Nakada). File 0001-Hash-store-return-old-value.patch added rosenfeld (Rodrigo Rosenfeld Rosas) wrote: > > And, what should be returned if the key wasn't set? > > Its default value? Also calling its default proc? MartinBosslet (Martin Bosslet) wrote: > Seems reasonable to me. To detect whether a key hasn't been set yet, > one would check for the presence of the default value. That > doesn't catch cases where a key with a default value is actually > set, but that seems fine to me. Voices against this? Calling default proc can be expensive. So I don't think it's good idea to call it always. A patch to separate Hash#store from Hash#[]=, and let it return the old value. ---------------------------------------- Feature #6219: Return value of Hash#store https://bugs.ruby-lang.org/issues/6219#change-25391 Author: MartinBosslet (Martin Bosslet) Status: Assigned Priority: Low Assignee: matz (Yukihiro Matsumoto) Category: core Target version: 3.0 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. -- http://bugs.ruby-lang.org/