Ruby on Rails：如何设置要更改的变量可以更改的变量？

Question

我想要做

current_user.allow_????? = true

哪里????? 可能是我想要的

我以前看过它做过..只是不记得在哪里，或所谓的东西。

Answer 1

foo = "bar"
current_user.send("allow_#{foo}=", true)

编辑：

您在评论中要求的是另一回事。 如果要获取常量，则应使用例如

role = "admin"
User.const_get(role)  

Answer 2

那是一个“魔术方法”，您可以在current_user对象上实现method_missing。 设计模式示例

#example method passed into computer builder class  
builder.add_dvd_and_harddisk  
#or     
builder.add_turbo_and_dvd_dvd_and_harddisk  

def method_missing(name, *args)  
  words = name.to_s.split("_")  
  return super(name, *args) unless words.shift == 'add'  
  words.each do |word|  
    #next is same as continue in for loop in C#  
    next if word == 'and'  
    #each of the following method calls are a part of the builder class  
    add_cd if word == 'cd'  
    add_dvd if word == 'dvd'  
    add_hard_disk(100000) if word == 'harddisk'  
    turbo if word == 'turbo'  
  end  
end