UnboundMethod example

unbound-method-example.rb

module M
  def foo
    puts "deinfed?(foo) => #{defined?(foo).inspect}"
    puts "method(:foo) => #{method(:foo) rescue $!}"
    p self
  end
end

a = "str-a"
a.extend(M)
m = a.method(:foo)

puts "===== m.call ====="
m.call
puts "=========="

ubm = m.unbind

b = "str-b"
puts "===== ubm.bind(b).call ====="
ubm.bind(b).call
puts "=========="

puts "===== ubm.bind(42).call ====="
ubm.bind(42).call
puts "=========="

z-result.txt

===== m.call =====
deinfed?(foo) => "method"
method(:foo) => #<Method: "str-a".foo>
"str-a"
==========
===== ubm.bind(b).call =====
deinfed?(foo) => nil
method(:foo) => undefined method `foo' for class `String'
"str-b"
==========
===== ubm.bind(42).call =====
deinfed?(foo) => nil
method(:foo) => undefined method `foo' for class `Integer'
42
==========