如何将函数提升异常转换为函数返回？ [英] How to convert functions raising exceptions to functions returning Either?

问题描述

假设我有几个引发异常的函数。我正在包装它们返回 [Throwable，< function return type>] 。 （让我们假设我需要 而不是尝试）。

  def fooWrapper（arg1：FooArg1，arg2：FooArg2）= 
 try Right（foo（arg1，arg2））catch {case NonFatal（e）=> left（e）} 
 
 def barWrapper（arg1：BarArg1，arg2：BarArg2，a3：BarArg3）= 
 try Right（bar（arg1，arg2，artg3））catch {case NonFatal e）=>左（e）} 
 
 ... 
  

现在我想编写一个通用的包装器来摆脱扩展代码。你会建议什么？

解决方案

我会写这样的形式：

  def wrap [Value]（f：=> Value）：[Value，Exception] = try {
右（f）.right 
} 
 catch {
 case ex：Exception => left（ex）.right 
} 
 
 def foo（arg1：FooArg1，arg2：FooArg2）= wrap {
 //以前在foo 
} 
  

但这不构成。 尝试更好。

更新：如果您只想处理正确的投影，然后只是返回正确的投影。现在它组成了。

Suppose I have a few functions that raise exceptions. I am wrapping them to return Either[Throwable, <function return type>]. (Let's assume I need Either rather than Try).

def fooWrapper(arg1: FooArg1, arg2: FooArg2) =
  try Right(foo(arg1, arg2)) catch { case NonFatal(e) => Left(e) }

def barWrapper(arg1: BarArg1, arg2: BarArg2, a3: BarArg3) =
  try Right(bar(arg1, arg2, artg3)) catch { case NonFatal(e) => Left(e) }

...

Now I would like to write a generic wrapper to get rid of the bolierpllate code. What would you suggest ?

解决方案

I would write something of the form like this:

 def wrap[Value](f: => Value): Either[Value, Exception] = try{
   Right(f).right
 }
 catch{
   case ex: Exception => Left(ex).right
 }

 def foo(arg1: FooArg1, arg2: FooArg2) = wrap{
   //anything I'd have written before in foo
 }

but this doesn't compose. Try is so much nicer.

Updated: If you only ever want to deal with the right projection, then just return the right projection. Now it composes.

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