From: shevegen@... Date: 2019-05-19T19:42:16+00:00 Subject: [ruby-core:92723] [Ruby trunk Feature#15863] Add `Hash#slice!` and `ENV.slice!` Issue #15863 has been updated by shevegen (Robert A. Heiler). I do not know how Hash#extract from Active* works but the name does not make to me a whole lot of sense to me; however had, we have Hash#slice already so I guess it may make sense to add .slice!; and if so, it may make sense to add it for ENV as ENV is very hash-like. But I may miss something altogether - this may be best to actually suggest to the upcoming developer meeting, since it is a fairly small request/possible change, anyway. (I don't feel I should add it myself because you suggested it so you should be in control over as to whether you want to suggest it or not - that is not my decision what you make of course. :)) The next meeting is at: https://bugs.ruby-lang.org/issues/15782 As for behaviour - this is not necessarily specific to your proposal alone, but I think ruby users will expect that the trailing "!" indicates a warning or rather an operation that may be "dangerous" or have side effects - the most usual one being modifying the receiver in place (or something like that). Not all methods have a trailing !, for example, replace() on class String. I think the bottom line is that matz wanted a simple visual cue/indicator for ruby. So I think whatever the feature request or desired change, I think the most natural assumption would be that a variant with ! will do precisely the same as the non-! variant, as action, but without modifying the object at hand. It is for this reason that I believe that .slice! could (or should) not model any other behaviour than what .slice() is doing right now. But as said, I may be missing something; perhaps there was a reason .slice!() was not added, I would not know. ---------------------------------------- Feature #15863: Add `Hash#slice!` and `ENV.slice!` https://bugs.ruby-lang.org/issues/15863#change-78082 * Author: bogdanvlviv (Bogdan Denkovych) * Status: Open * Priority: Normal * Assignee: * Target version: ---------------------------------------- ## Add `Hash#slice!` In https://bugs.ruby-lang.org/issues/8499 we added `Hash#slice`. `Hash#slice!` removes and returns the key/value pairs matching the given keys: ```ruby h = {a: 100, b: 200, c: 300} h.slice!(:a) # => {:a=>100} h # => {:b=>200, :c=>300} h.slice!(:b, :c, :d) # => {:b=>200, :c=>300} h # => {} ``` Note that, this method reflects the behavior of Active Support's `Hash#extract!` method that was added in 2009, see https://github.com/rails/rails/commit/8dcf91ca113579646e95b0fd7a864dfb6512a53b ```ruby h = {a: 100, b: 200, c: 300} h.extract!(:a) # => {:a=>100} h # => {:b=>200, :c=>300} h.extract!(:b, :c, :d) # => {:b=>200, :c=>300} h # => {} ``` (There is a proposal to add `Hash#extract` to Ruby - https://bugs.ruby-lang.org/issues/15831, but it has another method signature) Active Support also has `Hash#slice!`, see https://api.rubyonrails.org/v5.2/classes/Hash.html#method-i-slice-21. It is quite different what this patch proposes, see how it works: ```ruby h = {a: 100, b: 200, c: 300} h.slice!(:a) # => {:b=>200, :c=>300} # AS Hash#slice! h # => {:a=>100} h.slice!(:b, :c, :d) # => {:a=>100} # AS Hash#slice! h # => {} ``` I think `Hash#slice!` in Ruby should work in the same way as `Hash#extract!` from Active Support, there is one argument: - https://bugs.ruby-lang.org/issues/8499#note-31 It should behave in the way `Hash#slice` does, except one thing `Hash#slice!` modifies the object. (See, for instance, how `Array#slice` and `Array#slice!` work, they return the same value) But I would like to discuss it more to choose the right behavior for the proposed method. (Maybe there are good arguments why we should add `Hash#slice!` with behavior as it is in Active Support) ## Add `ENV.slice!` The method removes and returns the key/value pairs matching the given keys. ```ruby ENV.slice!("PORT", "RAILS_ENV") # => {"PORT"=>"3000", "RAILS_ENV"=>"development"} ``` Pull Request: https://github.com/ruby/ruby/pull/2195 Patch: https://patch-diff.githubusercontent.com/raw/ruby/ruby/pull/2195.patch -- https://bugs.ruby-lang.org/ Unsubscribe: