c# - 何时在 c# 中重新抛出异常？

Question

我已经阅读了为什么我们需要抛出异常并重新抛出它。但是我对何时重新抛出异常感到困惑？我在 CalculationOperationNotSupportedException catch 中放入 throw 时添加了一个示例，之后，我将 Stack Trace 与 Rethrowing 和不 Rethrowing 进行了比较。 99% 都是一样的，但是当您重新抛出异常时，它只会添加位置。
当然，如果你准确地进行了两次堆栈跟踪。第 35 行是“抛出”位置编号，第 28 行是 int result =calculator.Calculate(number1, number2, operation);
我认为 Stack Trace 不在这里重新抛出更好。你怎么看？

Stack Trace without rethrowing(throw) 我评论了它。

at ConsoleCalculator.Calculator.Calculate(Int32 number1, Int32 number2, String operation) in C:\Users\Behnam\Desktop\c-sharp-error-handling-exceptions\06\demos\after\03UsingExceptions\ConsoleCalculator\Calculator.cs:line 25 at ConsoleCalculator.Program.Main(String[] args) in C:\Users\Behnam\Desktop\c-sharp-error-handling-exceptions\06\demos\after\03UsingExceptions\ConsoleCalculator\Program.cs:line 28

在 catch 中重新抛出的堆栈跟踪 (CalculationOperationNotSupportedException ex)

at ConsoleCalculator.Calculator.Calculate(Int32 number1, Int32 number2, String operation) in C:\Users\Behnam\Desktop\c-sharp-error-handling-exceptions\06\demos\after\03UsingExceptions\ConsoleCalculator\Calculator.cs:line 25 at ConsoleCalculator.Program.Main(String[] args) in C:\Users\Behnam\Desktop\c-sharp-error-handling-exceptions\06\demos\after\03UsingExceptions\ConsoleCalculator\Program.cs:line 35

public int Calculate(int number1, int number2, string operation)
{
    string nonNullOperation = 
        operation ?? throw new ArgumentNullException(nameof(operation));

    if (nonNullOperation == "/")
    {
        try
        {
            return Divide(number1, number2);
        }
        catch (ArithmeticException ex)
        {
            throw new CalculationException("An error occurred during division", ex);
        }
    }
    else
    {
        throw new CalculationOperationNotSupportedException(operation);
    }
}

static void Main(string[] args)
{
    var calculator = new Calculator();
    int number1=1;
    int number2=1;
    string operation = "+";
    try
    {
        int result = calculator.Calculate(number1, number2, operation);
        DisplayResult(result);
    }
    catch (CalculationOperationNotSupportedException ex)
    {
        // Log.Error(ex);
        WriteLine(ex);
        throw;
    }
}

Answer 1

有两篇关于我经常链接的主题的文章。我认为它们是必读的。

https://blogs.msdn.microsoft.com/ericlippert/2008/09/10/vexing-exceptions/

https://www.codeproject.com/Articles/9538/Exception-Handling-Best-Practices-in-NET

基本上，如果您无法处理异常，则不应捕获异常。但有时，您必须对任何有关 Exception 的规则进行异常(exception)处理(没有双关语意)。您可能需要更广泛地捕捉，然后将“捕捉和释放”应用于您获得的额外异常。例如，这是我尝试复制 TryParse:

//Parse throws ArgumentNull, Format and Overflow Exceptions.
//And they only have Exception as base class in common, but identical handling code (output = 0 and return false).

bool TryParse(string input, out int output){
  try{
    output = int.Parse(input);
  }
  catch (Exception ex){
    if(ex is ArgumentNullException ||
      ex is FormatException ||
      ex is OverflowException){
      //these are the exceptions I am looking for. I will do my thing.
      output = 0;
      return false;
    }
    else{
      //Not the exceptions I expect. Best to just let them go on their way.
      throw;
    }
  }

  //I am pretty sure the Exception replaces the return value in exception case. 
  //So this one will only be returned without any Exceptions, expected or unexpected
  return true;
}