Make Kernel methods to be available as module functions

[pocke]

This pull request makes Kernel methods to be available as module functions.

Problem

Most Kernel methods are available as module functions, but currently any Kernel methods aren't.

For example, Kernel.puts "Hello" is a valid Ruby code but Steep complain it.
Because Kernel.puts is typed as a private method accidentally.

Solution

Most methods are module functions, but it is not all methods. So I need to extract the target methods in the beginning.

I extracted the target methods with the following code on IRB.

Kernel.methods.map { Kernel.method(_1) }.select { _1.owner == Kernel.singleton_class }.map(&:name)
# => [:pp, :Pathname, :local_variables, :rand, :srand, :sprintf, :format, :Integer, :String, :Array, :Hash, :warn, :trap, :test, :require, :raise, :fail, :global_variables, :__method__, :__callee__, :__dir__, :require_relative, :autoload, :autoload?, :system, :eval, :iterator?, :block_given?, :catch, :throw, :loop, :exec, :binding, :gets, :abort, :proc, :lambda, :spawn, :Rational, :caller, :caller_locations, :set_trace_func, :exit!, :trace_var, :untrace_var, :at_exit, :Complex, :fork, :URI, :select, :load, :exit, :`, :syscall, :open, :printf, :print, :putc, :puts, :readline, :readlines, :p, :Float, :sleep]

And I changed the methods kinds to self? for the above methods.

Note

I found some missing methods while I updated the RBS.
The following methods are available as Kernel's singleton methods, but RBS doesn't have any definitions.

• trap
• spawn
• set_trace_func
• trace_var
• untrace_var

So we need to add them to kernel.rbs as module functions, but this pull request doesn't add them because of out of scope.
I'll work on them with another pull request.

--

I noticed this problem with this bloc post. Thanks! https://narazaka.hatenablog.jp/entry/2020/12/26/Ruby_3.0%E3%81%AE%E9%9D%99%E7%9A%84%E5%9E%8B%E5%AE%9A%E7%BE%A9%E3%82%92TypeScript%E3%81%BF%E3%81%9F%E3%81%84%E3%81%AB%E3%83%A9%E3%82%A4%E3%83%96%E3%83%A9%E3%83%AA%E3%81%AB%E6%9B%B8%E3%81%84%E3%81%A6

[pocke]

Well, this change doesn't affect the accessibility of Kernel.puts singleton method.

The accessibility is still private with this patch.

$ exe/rbs method --singleton Kernel puts
::Kernel.puts
  defined_in: ::Kernel
  implementation: ::Kernel
  accessibility: private
  types:
      (*untyped arg0) -> ::NilClass

I guess the cause is a mismatch of Ruby's module_function and RBS's self?.

In Ruby, module_function works as the following:

• Make the instance method private
• Create an alias of the instance method as singleton method, but it is public.

But in RBS, I guess self? syntax doesn't affect accessibility. Kernel module has private member on the top of the module definition, so both of instance and singleton methods are private.

---

So, I think we have two solutions to fix this problem.

First, we can define private instance methods and public singleton methods by hand.
For example:

# kernel.rbs

module Kernel : BasicObject
  private
  def puts: (*untyped) -> nil
  public
  def self.puts: (*untyped) -> nil

  # ...
end

It works, but I think it is not efficient.

Second, we can change the semantics of self? to make it the same with Ruby's module_function.
I guess we can write Kernel's definition and other module_function efficiently with this change.
But it may introduce an incompatibility, and it means self? syntax ignores public and private syntax. Maybe it introduce confusion about accessibility.

module M
  private
  def self?.foo: () -> untyped
end

# M.foo is public or private???

[soutaro]

[Goodcheck] Prefer boolish over bool for method arguments and block return values (view)

See the doc below:
https://github.com/ruby/rbs/blob/78d04a2db0f1c4925d2b13c2939868edf9465d6c/docs/syntax.md#bool-or-boolish

Rule
rbs.prefer_boolish

You can close this issue if no need to fix it. Learn more.

👍 true of false is required here.

[soutaro]

[Goodcheck] Prefer boolish over bool for method arguments and block return values (view)

See the doc below:
https://github.com/ruby/rbs/blob/78d04a2db0f1c4925d2b13c2939868edf9465d6c/docs/syntax.md#bool-or-boolish

Rule
rbs.prefer_boolish

You can close this issue if no need to fix it. Learn more.

I closed this issue, because:

• When you strictly want true | false.

[soutaro]

Resolved the conflict caused by deletion of iterator? #569