[英]F#: Custom exceptions. Is there a better way to overload the exception type?
我有一個簡單的自定義異常,如下所示,但我不喜歡使用Throw函數,我真的不喜歡同時使用Throw和Throw2函數。 有更優雅的方式嗎? 有沒有一種方法可以在沒有中間函數的情況下直接拋出MyError或Error?
#light
module Utilities.MyException
type MyError(code : int, msg : string) =
member e.Msg = msg
member e.Code = code
new (msg : string) = MyError(0, msg)
exception Error of MyError
let public Throw (msg : string) =
let err = new MyError(msg)
raise (Error err)
let public Throw2 (code : int) (msg : string) =
let err = new MyError(code, msg)
raise (Error err)
我正在使用它,如下所示,但我想使用其中一個不起作用的變體
Throw(System.String.Format("Could not parse boolean value '{0}'", key))
//The string isn't of the correct type for Error
//raise(Error(System.String.Format("Could not parse boolean value '{0}'", key)))
//MyError isn't compatible with System.Exception
//raise(MyError(System.String.Format("Could not parse boolean value '{0}'", key)))
只需忽略exception
構造並直接定義異常類 - 即從System.Exception
派生的異常類,如在C#中:
type MyError(code : int, msg : string) =
inherit Exception(msg)
member e.Code = code
new (msg : string) = MyError(0, msg)
raise(MyError("Foo"))
raise(MyError("Foo", 1))
請注意,我刪除了Msg
成員,因為Exception
已經具有等效的Message
屬性。
我不清楚你究竟是在追求什么,但這對你有什么用?
exception Error of int * string
let ErrorC(s) = Error(0,s)
let F() =
try
let key = true
raise <| Error(42, System.String.Format("Could not parse '{0}'", key))
raise <| ErrorC(System.String.Format("Could not parse '{0}'", key))
with Error(code, msg) ->
printfn "%d: %s" code msg
如何將MyError重新定義為記錄並使用記錄語法記錄錯誤,例如: -
type MyError =
{ Msg: string;
Code: int }
exception Error of MyError
raise <| Error { Msg = ( sprintf "Could not parse boolean value '%b'" key );
Code = code }
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