Ractor.[] and Ractor.[]=

`Ractor#[]/[]=` is only for accessors to the current ractor, so that
`Ractor.[]/[]=` is simpler.
[Feature #20715]

Author: ko1

ractor.rb

@@ -834,16 +834,26 @@ def self.make_shareable obj, copy: false
     end
   end
 
-  # get a value from ractor-local storage
+  # get a value from ractor-local storage of current Ractor
   def [](sym)
     Primitive.ractor_local_value(sym)
   end
 
-  # set a value in ractor-local storage
+  # set a value in ractor-local storage of current Ractor
   def []=(sym, val)
     Primitive.ractor_local_value_set(sym, val)
   end
 
+  # get a value from ractor-local storage of current Ractor
+  def self.[](sym)
+    Primitive.ractor_local_value(sym)
+  end
+
+  # set a value in ractor-local storage of current Ractor
+  def self.[]=(sym, val)
+    Primitive.ractor_local_value_set(sym, val)
+  end
+
   # returns main ractor
   def self.main
     __builtin_cexpr! %q{