respond_to? vs respond_to_missing?

respond_to.rb

# First check is always #respond_to? , if it returns false, then #respond_to_missing? will be called, otherwise #respond_to_missing? 
# will never be called. For all regular methods( which has been created by def, define_method, in C-implementation etc), thus we get
# false, while we pass the method name to the #respond_to_missing?. Because, first check has been done inside #respond_to?, and it
# returns true. That's why second output is [true, false]. Because, #foo is a regular method.

# Now why the second output is [true, true] ? The reason, I already explained, again #baz is not a regular method, so first check in
# #respond_to? return false, thus check goes to #respond_to_missing?. As I implemented it, so as per the implementations it is giving
# true, which in turn caused #respond_to? method to returns to true.


#!/usr/bin/env ruby

class Foo
  def foo
    12
  end

  def method_missing(meth, *args, block)
    if meth.to_s.start_with? "ba"
      "#{meth} has been created by #{__method__}"
    else
      super
    end
  end

  def respond_to_missing?(meth, include_all) 
    if meth.to_s.start_with? "ba"
      true
    else
      super
    end
  end
end



begin
p [Foo.new.respond_to?(:baz),Foo.new.send(:respond_to_missing?, :baz, true)]
p [Foo.new.respond_to?(:foo),Foo.new.send(:respond_to_missing?, :foo, true)]
rescue Exception
  puts "#{$!} (#{$!.class})"
  $stdout.flush
  raise $!
end


# >> [true, true]
# >> [true, false]