From: "stuyam (Stuart Yamartino) via ruby-core" <ruby-core@...>
Date: 2023-12-21T20:47:09+00:00
Subject: [ruby-core:115843] [Ruby master Feature#20027] Add Range Deconstruction

Issue #20027 has been updated by stuyam (Stuart Yamartino).


I like your suggestion of the `#begin_and_end` method, that solves the performance issues, it also then relies on solely array deconstruction doing it's own job which is nice! I could see `#begin_and_end` being useful for something like an ORM where you need the endpoints to do a `BETWEEN` in SQL or something and it would allow you to more easily deconstruct a range when a range is being used more as an object to store the endpoints rather than an object to ask questions about things in between the endpoints etc.

----------------------------------------
Feature #20027: Add Range Deconstruction
https://bugs.ruby-lang.org/issues/20027#change-105799

* Author: stuyam (Stuart Yamartino)
* Status: Rejected
* Priority: Normal
----------------------------------------
Ranges are a powerful tool in ruby. A common range I use is a date range such as `(Date.yesterday..Date.tomorrow)`. A range will often be passed around to methods because the dates hold meaning together such as a timeframe for a table filter.
Often I want to grab the original values out of a range like:
```ruby
timeframe = (Date.yesterday..Date.tomorrow)
start_date = timeframe.begin
end_date = timeframe.end

#=> start_date = yesterday
#=> end_date = today
```

Similar to array and hash deconstruction I thought it would be useful to support range deconstruction like this:
```ruby
start_date, end_date = (Date.yesterday..Date.tomorrow)

#=> start_date = yesterday
#=> end_date = today
```


This would also work for endless or beginless ranges since the beginning and end are just nil in those cases:
```ruby
start_date, end_day = ..Date.tomorrow

#=> start_date = nil
#=> end_date = tomorrow
```

You could do this now using `to_a` like:
```ruby
start_date, *middle_dates, end_date = (Date.new(2000,1,1)..Date.new(2023,1,1).to_a
```
However this has unnecessary performance issues by converting the range to an array especially if the range spans a large period, `middle_dates` would hold a very large array. Also if the range resulted in an array with 2 values, `end_date` would be nil and this wouldn't actually work to get the begin and end values.

I think this provides a simple interface for a common pattern of deconstructing ranges into their beginning and end values. It would be useful for ranges regardless of date ranges or other types of ranges since they are essentially tuples. Would love to know what others think about this <3



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