Feature #20080
Updated by stuyam (Stuart Yamartino) 10 months ago
Followup Reference: #20027 **Updated Proposal:** (based on many wonderful suggestions!) 1. Call the method `#bounds`. ```ruby first, last = (1..300).bounds # => [1, 300] first, last = (300..1).bounds # => [300, 1] first, last = (..300).bounds # => [nil, 300] first, last = (1..).bounds # => [1, nil] ``` 2. Add `exclude_end?` support so re-hydration of Range works: ```ruby b = (1..2).bounds #=> [1,2] Range.new(*b) #=> 1..2 b = (1...2).bounds #=> [1,2,true] Range.new(*b) #=> 1...2 ``` I did a better job of outlining use cases in this comment below so I will let that speak for itself: https://bugs.ruby-lang.org/issues/20080#note-3 **Original Proposal:** This feature request is to implement a method called `#begin_and_end` on `Range` that returns an array of the first and last value stored in a range: ```ruby (1..300).begin_and_end #=> [1, 300] first, last = (300..1).begin_and_end first #=> 300 last #=> 1 ``` I believe this would be a great addition to Ranges as they are often used to pass around a single object used to hold endpoints, and this allows easier retrieval of those endpoints. This would allow easier deconstruction into start and end values using array deconstruction as well as a simpler way to serialize to a more primitive object such as an array for database storage. This implementation was suggested by @mame in my initial feature suggestion regarding range deconstruction: https://bugs.ruby-lang.org/issues/20027 This implementation would work similar to how `#minmax` works where it returns an array of two numbers, however the difference is that `#minmax` doesn't work with reverse ranges as @Dan0042 pointed out in the link above: ```ruby (1..42).minmax #=> [1, 42] (42..1).minmax #=> [nil, nil] ``` **Updated Proposal:** (based on many wonderful suggestions!) 1. Call the method `#bounds` rather than `#begin_and_end`. ```ruby first, last = (1..300).bounds # => [1, 300] first, last = (300..1).bounds # => [300, 1] first, last = (..300).bounds # => [nil, 300] first, last = (1..).bounds # => [1, nil] ``` 2. Add `exclude_end?` support so re-hydration of Range works: ```ruby b = (1..2).bounds #=> [1,2] Range.new(*b) #=> 1..2 b = (1...2).bounds #=> [1,2,true] Range.new(*b) #=> 1...2 ``` 3. Options for controlling when and if `exclude_end?` is included: ```ruby # automatic by default, only shows when exclude_end? is true # useful for re-hydration and doing the right thing in most cases (1..2).bounds #=> [1,2] (1...2).bounds #=> [1,2,true] # show exclude_end? always # useful for mixed range usage in logic that needs to know the end, or storing in a table where you want to be explicit (1..2).bounds(true) #=> [1,2,false] (1...2).bounds(true) #=> [1,2,true] # never show exclude_end? # useful for sending to a front end or something where you just need the bounds (1..2).bounds(false) #=> [1,2] (1...2).bounds(false) #=> [1,2] ``` Option 3 here feels sort of unnecessarily actually, I think if you want something explicit in those formats it would be easy to implement, though I could still see it being useful to require a format. I like that option 2. makes it do the dynamic thing which supports loading and unloading range and allows you to represent the range in an array etc.