PowerShell 技能连载 - 高级错误处理：重新抛出异常

在处理错误时，您有时会希望将原始的异常替换成您自己的。以下是一个例子：

function Do-Something
{
  # function uses internal error handling
  try
  {
    Get-Process -Name NotThereOhWell -ErrorAction Stop
  }
  # catch this error type
  catch [Microsoft.PowerShell.Commands.ProcessCommandException]
  {
    $oldE = $_.Exception

    # handle the error, OR SHOWN HERE: issue a new exception to the caller
    $newE = New-Object -TypeName System.InvalidOperationException('Do-Something: A fatal error occured', $oldE)
    Throw $newE
  }
}

# function will encounter an internal error
# error message shows error message generated by function instead
Do-Something

调用者看到的内容如下：

PS C:\>  Do-Something
Do-Something: A fatal  error occured
At line:18 char:5
+     Throw $newException
+     ~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : OperationStopped: (:) [],  InvalidOperationException
    +  FullyQualifiedErrorId : Do-Something: A fatal error occured

如果调用者也用一个错误处理函数来接收它，则会出现这种情况：

try
{
  Do-Something
}
catch [System.InvalidOperationException]
{
  [PSCustomObject]@{
    Message = $_.Exception.Message
    Originalmessage = $_.Exception.InnerException.Message
    }
}

结果看起来如下：

Message                             Originalmessage
-------                             ---------------
Do-Something: A fatal error occured Cannot find a process with the name
                                    "NotThereOhWell". Verify the process name
                                    and call the cmdlet again.

这样调用者可以看到返回的错误信息，并且经过内部处理之后，还可以传递原始的错误信息。