class Array
  def iterate!(&code) #注意这里用了&符号
    self.each_with_index do |n,i|
      self[i] = code.call(n)
    end
  end
end

arr = [1,2,3,4]

arr.iterate! do |n|
  n ** 2
end
 
#[1, 4, 9, 16]

def math_by_anonymouse_block(a,b)
    yield a,b
end

def math_by_proc(a,b,a_proc)
    a_proc.call(a,b)
end

def math_by_named_block(a,b,&namedblock)

		puts "math_by_proc a,b,namedblock"
		puts namedblock.class # &namedblock 是一个区块，namedblock （去掉&）是一个proc，&操作符是个切换开关。
		puts math_by_proc a,b,namedblock
		puts "======="

		#lambda
		mylambda = lambda &namedblock
    puts mylambda.class
    puts math_by_anonymouse_block a,b,&mylambda
		#哈哈，下面这样也可以
		puts "math_by_proc a,b,mylambda"
		puts math_by_proc a,b,mylambda
		puts "======="

		#proc
    myproc = proc &namedblock
    puts myproc.class
    puts math_by_anonymouse_block a,b,&myproc
		#哈哈，下面这样也可以
		puts "math_by_proc a,b,myproc"
		puts math_by_proc a,b,myproc
		puts "======="

    #puts &namedblock.class

		#区块不能直接赋值给一个变量。但是可以通过方法来传递
    #myblock = &namedblock   #运行不通
    #puts myblock.class
		#所以我们用这种方式
		puts "math_by_anonymouse_block"
		puts math_by_anonymouse_block a,b,&namedblock
		puts "======="

end

math_by_named_block(2,3) {|x,y| x*y}

---------- ruby run ----------
math_by_proc a,b,namedblock
Proc
6
=======
Proc
6
math_by_proc a,b,mylambda
6
=======
Proc
6
math_by_proc a,b,myproc
6
=======
math_by_anonymouse_block
6
=======

输出完成 (耗时 0 秒) - 正常终止

def my_noyield

　　puts "leave me alone. no yield !"

end

def my_yield
　　　　　　　　　　
　　puts "I call you! come on"
　　yield

end

my_noyield { puts "I'm coming！"}

my_yield { puts "I'm coming！"}

def my_third(&myproc)
	puts "I call you! come on"
	yield
end

my_third { puts "I'm coming！"}

def my_fourth (&myproc)
	puts "I call you! come on"
	myproc.call
end

my_fourth { puts "I'm coming！"}

def my_fivth (&myproc)
	puts "I call you! come on"
	#&&myproc.call  这个不行，不能反转两次？
	c_proc = proc &myproc
	c_proc.call
end

my_fivth { puts "I'm coming！"}

def my_sixth (&myproc)
	puts "I call you! come on"
	c_proc = lambda &myproc
	c_proc.call
end

my_sixth { puts "I'm coming！"}