# 法一
inc = Proc.new { | x | x + 1}
inc.call(2) #=> 3

# 法二
inc = lambda {| x | x + 1 }
inc.call(2) #=> 3

# 法三
inc = ->(x) { x + 1}
inc.call(2) #=> 3

# 法四
inc = proc {|x| x + 1 }
inc.call(2) #=> 3

def my_method(&the_proc)
  the_proc
end

p = my_method {|name| “Hello, #{name} !”}
p.class  #=> Proc
p.call(“Bill”)  #=> “Hello,Bill”


def my_method(greeting)
  “#{greeting}, #{yield}!”
end

my_proc = proc { “Bill” }
my_method(“Hello”, &my_proc)

 def f(...)
  ...
  yield
  ...
 end

 def f(..., &p)
  ...
  p.call
  ...
 end

 def f(..., &p)
  instance_eval &p
  ...
 end

 def f(..., &p)
  ...
  defime_method m, &p
  ...
 end

 def f(..., &p)
  instance_eval p
 end

 def f(..., p)
  instance_eval p.call
 end

 def f(..., &p)
  instance_eval do
   p.call
  end
 end

 def f(...)
  instance_eval do
   yield
  end
 end

 def f(...)
  instance_eval yield
 end