Is it possible to have a helper function cause the calling function to return/exit?-CodePudding

I have a large function/sub that does a ton of validations and error checking early on before going into an ETL design pattern. So I am using "C/C "-esque error checking where you want to "fail early", i.e. if the validations fail, I call Return (same as Exit Sub) asap and no further code is executed.

Notice the repeating code in the VB.net code below:

If fn Is Nothing Then
    lblDataError.Text = "<b>Error!</b> Could not upload your file. <b>Reason:</b> Filename is blank, please press the <kbd>Browse</kbd> button first to select the file, then press <kbd>Upload</kbd>."
    divFail.Visible = True
    Return
ElseIf Path.GetExtension(fn).ToLower() <> ".csv" Then
    lblDataError.Text = "<b>Error!</b> Could not upload your file. <b>Reason:</b> Filename extension must be <kbd>.csv</kbd>."
    divFail.Visible = True
    Return
Else
    For Each badChar As Char In System.IO.Path.GetInvalidFileNameChars
        If InStr(fn, badChar) > 0 Then
            lblDataError.Text = "<b>Error!</b> Could not upload your file. <b>Reason:</b> Filename contains invalid character(s)."
            divFail.Visible = True
            Return
        End If
    Next
End If

Is it possible to make a helper function such that it causes the calling function to return? If this isn't possible in .NET, do any languages support this?

Public Function Fail(customErrorMessage as String)
    lblDataError.Text = "<b>Error!</b> " & customErrorMessage 
    divFail.Visible = True
    Return Return  'This line should cause the calling function to return.
End Function

Or should I just use a Boolean and do an if-statement after all the validations because this isn't possible?

CodePudding user response：

I suggest you look at using try/catch and exceptions. Supported in C# and pretty much any other language I can think of.

CodePudding user response：

Building on Steve's idea... to call your fail function inside each of your validations. You know you're going to return, so something like this:

If fn Is Nothing Then
    Call Fail("<b>Error!</b> Could not upload your file. <b>Reason:</b> Filename is blank, please press the <kbd>Browse</kbd> button first to select the file, then press <kbd>Upload</kbd>.")
    Return
ElseIf ...