From: mame@... Date: 2020-06-18T09:37:38+00:00 Subject: [ruby-core:98865] [Ruby master Feature#16456] Ruby 2.7 argument delegation (...) should be its own kind of parameter in Method#parameters Issue #16456 has been updated by mame (Yusuke Endoh). Adding a new type of parameters will break existing code. In fact, if we add a new type `:delegate`, the Sorbet code written in #note-8 will `raise "Unknown parameter type: #{type}"`. So, we must be careful. Currently, `(...)` parameter generates a unique indicator `[:rest, :*]`. Note that it uses an invalid variable name `:*`, so it is not produced by other parameters than `(...)`. Thus, without ambiguity, it is already able to determine if `(...)` parameter is used or not by checking if the result of `Method#parameters` includes `[:rest, :*]`. So, currently, I don't see a strong reason to add a new type. That being said, feeling is important for Ruby. Changing `:*` to `:"..."` may be acceptable, though it brings incompatibility. I have no idea if it is worth or not. ---------------------------------------- Feature #16456: Ruby 2.7 argument delegation (...) should be its own kind of parameter in Method#parameters https://bugs.ruby-lang.org/issues/16456#change-86230 * Author: aaronc81 (Aaron Christiansen) * Status: Open * Priority: Normal ---------------------------------------- A method defined with `...` as its parameter list is equivalent to one defined with `*args, &blk`, according to `Method#parameters`. ```ruby def foo(...); end p method(:foo).parameters # => [[:rest, :*], [:block, :&]] ``` Even in Ruby 2.7, `...` and `*args, &blk` are not *quite* equivalent as the latter may produce a warning where the former does not. In Ruby 3.0 and beyond, `...` and `*args, &blk` will have a substantial semantic difference. Due to this, I don't consider the current behaviour of `Method#parameters` particularly ideal when dealing with methods using this new syntax. If the goal of `...` is to be a "delegate everything" operator, even when parameter passing is changed like in Ruby 3.0, I would propose that `Method#parameters` considers it a unique type of parameter. For example: ```ruby def foo(...); end p method(:foo).parameters # => [[:delegate, :"..."]] ``` -- https://bugs.ruby-lang.org/ Unsubscribe: