refer: ruby on rails - What does .call do? - Stack Overflow

Ruby使用call 可以调用方法或者proc

m = 12.method("+")
# => `method` gets the `+` method defined in the `Fixnum` instance
# m.class 
# => Method

m.call(3)    #=> 15
# `3` is passed inside the `+` method as argument 
m.call(20)   #=> 32

send方法也可以调用方法，在本地写一个测试：

def say_hi

  puts "hihi"

end

def say_goodbye

  puts "goodbye"

end

# 使用send方式调用方法

name = "say_hi"

send(name)

m = 12.method("+")

# => `method` gets the `+` method defined in the `Fixnum` instance

# m.class

# => Method

m.call(3)    #=> 15

puts m.call(3)

# `3` is passed inside the `+` method as argument

m.call(20)   #=> 32

puts m.call(20)

运行：ruby hi.rb

得到输出：

hihi

15

32