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Recognizing handled exceptions

DerikWhittakerDerikWhittaker Posts: 3
I ran ExceptionHunter on some test code to see what it would do. When i was provided with the possible exceptions, I added and if statement that threw the correct exceptions the condition was met, however when I run ExcpetionHunter again, it still shows me that the exception condition exists.

Here is my code
No exception handling
public bool StringParameterMethod( string value )
{
if ( value.Equals( "ABC" ) )
{
return true;
}
return false;
}

With exception handling
public bool StringParameterMethod_Valid(string value)
{

if (value == null) { throw new NullReferenceException("The provided parameter {value} was null"); }
if (value.Length == 0) { throw new ArgumentOutOfRangeException("Value", value, "The provided parameter {value} did not contain a valid value." ); }

if (value.Equals("ABC"))
{
return true;
}

return false;
}

Am I doing something wrong?
Derik Whittaker
http://devlicio.us/

Comments

  • Options
    Derik.

    With the following code Exception Hunter will tell you you throw all of the exceptions for Equals as well as NullReferenceException/ArgumentOutOfRangeException (Unless it can determine that any of them will never be thrown).

    public bool StringParameterMethod_Valid(string value)
    {

    if (value == null) { throw new NullReferenceException("The provided parameter {value} was null"); }
    if (value.Length == 0) { throw new ArgumentOutOfRangeException("Value", value, "The provided parameter {value} did not contain a valid value." ); }

    if (value.Equals("ABC"))
    {
    return true;
    }

    return false;
    }

    To stop exceptions you would need to add a try...catch handlers to do somthing when the exceptions are thrown, generally you might want to do this in the functions which call StringParameterMethod_Valid or you might want to wrap your call to Equals with a try...catch and return false, IE:

    public bool StringParameterMethod_Valid(string value)
    {

    try
    {

    if (value.Equals("ABC"))
    {
    return true;
    }

    } catch (ArgumentOutOfRangeException argumentOutOfRangeException)
    {
    // Log if needed
    return false; // not valid
    }
    catch(NullReferenceException nullReferenceException)
    {
    //Log as needed
    return false; // not valid
    }

    return false;
    }

    HTH,

    James
    James Moore
    Head of DBA Tools
    Red Gate Software Ltd
  • Options
    James,

    I understand what you are saying, I just don't agree with it. I should NOT have to put a try-catch in order for ExceptionHunter to think I have handled the possible exception case.

    From my point of view, this violates the fail-fast concept. If i only have a try-catch, then I am not doing my part in checking for possible known failures before processing. I understand that I need try-catches, but try-catches should be for unknown (at development time) exceptions.

    I really believe the product should notice the fact that the exception scenario has been handled show you that.
    Derik Whittaker
    http://devlicio.us/
  • Options
    Derik,

    When I run analysis on the following code I get told a nullreferenceexception can be thrown:

    private static bool MyFunction(string p)
    {

    if (p.Equals("ABC"))
    {
    return true;
    }

    return false;
    }

    If I add

    if (p == null)
    {
    return false;
    }

    Before the p.Equals I get told that no exceptions can be thrown.

    With your code I would expect to be told a NullReferenceException or ArgumentOutOfRangeException can be thrown as you are throwning them explicitly (their source will be different from your original example without error handling but they are still thrown).

    I am not quite sure what output you are expecting from your second example.

    James
    James Moore
    Head of DBA Tools
    Red Gate Software Ltd
  • Options
    If i have some code like thus

    private static string GetDateString(DatePicker date)
    {
    try
    {
    if (date != null && date.SelectedDate != null)
    {
    return date.SelectedDate.Value.ToString("yyyy/MM/dd");
    }

    return DateTime.MinValue.ToString("yyyy/MM/dd");
    }
    catch (NullReferenceException)
    {
    return DateTime.MinValue.ToString("yyyy/MM/dd");
    }
    }

    I get an error that System.Windows.Controls.DataPicker.get_SelectedDate() may raise a NullReferenceExcpetion

    I have clearly dealt with it twice, I don't see why exception hunter is still showing it as an unhandled exception.
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