在OCaml的OOP构造中即时确定类型 [英] Determining type on the fly in OCaml's OOP construct

问题描述

我正在学习OCaml的OOP构造，并在今天实现了部分实现，直到我意识到我不知道如何在不使用对象外部使用type关键字的情况下表示多态匹配语句.

I am learning about OCaml's OOP constructs and partially implemented this today until I realized I have no idea how to represent a polymorphic match statement without using the type keyword outside of the object.

class bar (param:string) =
object (code)

end;;

class foo param =
object (code)
 initializer 
  match param with
   string -> Printf.printf "param is a string"
   | bar -> Printf.printf "param is a bar"     
end;;

let b = new bar "a string";;
let f1 = new foo "test";;
let f2 = new foo b;;

是否可以实时确定传递的对象类型?

Is it possible to determine the type of object passed in on-the-fly?

推荐答案

该匹配除了将'param'绑定到'string'之外没有做任何事情，ocaml应该说不使用第二个匹配项.我相信您必须使用变体类型来进行匹配.以下是使用多态变体类型的示例.

That match isn't doing anything but binding 'param' to 'string', ocaml should say that the second match isn't used. I believe you'll have to use variant types to do the matching. Below is an example using polymorphic variant types.

class bar (param:string) =
  object (code)
end

class foo param =
  object (code)
  initializer 
    match param with
    | `String str -> Printf.printf "param is a string"
    | `Bar bar -> Printf.printf "param is a bar"     
end

let b = new bar "a string"
let f1 = new foo (`String "test")
let f2 = new foo (`Bar b)

这篇关于在OCaml的OOP构造中即时确定类型的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！