Feature #16425: Add Thread#dig

• Status: Open
• Assignee: -
• Target version: -

[nobu (Nobuyoshi Nakada)]

Thread has #[] method like as Array, Hash, Struct and so on, but no #dig.

For instance, PP::PPMethods#check_inspect_key in pp.rb can be simplified with the combination of this method and safe navigation operator.

From

    def check_inspect_key(id)
      Thread.current[:__recursive_key__] &&
      Thread.current[:__recursive_key__][:inspect] &&
      Thread.current[:__recursive_key__][:inspect].include?(id)
    end

To

    def check_inspect_key(id)
      Thread.current.dig(:__recursive_key__, :inspect)&.include?(id)
    end

Patch: https://github.com/ruby/ruby/pull/2756

[shevegen (Robert A. Heiler)]

I think the use case has been described and ruby users may agree
that this could be an improvement (e. g. such as the example given
by nobu for more succinct code).

#dig on Array, Hash and Struct makes sense; for Thread perhaps the
net benefit may be a bit more abstract (I guess the most common
use case for .dig will be for Array and then possibly Hash ... or
vice versa). The more relevant question may then be a language
design question, e. g. whether matz thinks that ruby users
should/could use dig for Threads too. From this point of view,
nobu's comparison makes sense (to me), e. g. the general []
method compared to dig. I myself use [] a lot for custom classes
since it is often nice to be able to use both Foobar.new and
Foobar[] - the latter even allowing slightly fewer characters. :)

IMO if matz is fine with Thread also being used/usable in that
way through .dig then I think nobu's suggestion makes sense,
so +1 about the idea.