是否可以声明一个以块为默认值的方法? [英] Is it possible to declare a method with block as default value?

问题描述

我想写一个带一个块的方法，如果没有给出块，则应该使用默认块.所以我想要这样的东西:

I want to write a method which takes a block and if no block given it should use a default block. So I want to have something like this:

def say_hello(name, &block = ->(name) { puts "Hi, #{name}" })
  # do something
end 

但是，当我尝试这样做时，出现语法错误.

But when I'm trying to do so I'm getting the syntax error.

我知道我可以使用

I know I can deal with my problem using block_given?. But I am interested in first approach. Am I missing something or this is just not possible?

推荐答案

某些答案建议使用block_given?，但是由于给出块的可能性不大，因此您可以使用nil或false只需使用||=.

Some answers suggest using block_given?, but since there is no possibility that a block would be nil or false when it is given, you can simply use ||=.

def say_hello(name, &block)
  block ||= ->(name){puts "Hi, #{name}"}
  # do something
end

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