Feature #8396: Allow easier destructuring of MatchData

• Status: Feedback
• Assignee: -
• Target version: -

[goshakkk (Gosha Arinich)]

=begin

(((I have opened ((<"a PR for this on GH @ rails/rails"|URL:https://github.com/ruby/ruby/pull/300>)) for this but @marcandre (Marc-Andre Lafortune) closed it and suggested I submit it here. I'll copy my proposal text here.)))

Currently, you can get something out of (({MatchData})) like this:

m = "2_apples".match /(\d+)_(apple|orange)s?/
count, thing = m[1], m[2]

or

, count, thing = "2_apples".match(/(\d+)(apple|orange)s?/).to_a

or

count, thing = "2_apples".match(/(\d+)_(apple|orange)s?/).captures

or, as @marcandre (Marc-Andre Lafortune) suggested, you can use splat operator

, count, thing = * "2_apples".match /(\d+)(apple|orange)s?/

However, this extra (({#to_a})) or (({#captures})) (or splat) that you have to add makes things slightly more verbose.

With this PR, it would be possible to do the following:

count, thing = "2_apples".match /(\d+)_(apple|orange)s?/

Which looks a bit cleaner and nicer. So what do you think?

=end

[matz (Yukihiro Matsumoto)]

I like the basic idea, but #to_ary is a method to convert into array implicitly, that means it expect the receiver provides array behavior. MatchObject does not behave like Array.
Maybe we should add another implicit conversion method for right hand side of multiple assignment.

Matz.

[jeremyevans0 (Jeremy Evans)]

This could be a use case for the @* method proposed in #2013.

[goshakkk (Gosha Arinich)]

=begin
Yep, the (({*@})) is a nice idea. Would be awesome if it could be used for splat-less destructuring as well. @matz (Yukihiro Matsumoto) what do you think about this?
=end

[naruse (Yui NARUSE)]

You can use named capture assigning

irb(main):005:0> /(?\d+)_(?apple|orange)s?/ =~ "2_apples"
=> 0
irb(main):006:0> count
=> "2"
irb(main):007:0> thing
=> "apple"

[zzak (zzak _)]

• Status changed from Open to Feedback