Exception derived class

[Jasleen]

I want to access the protected member hresult of the Exception class, so I
derived my own class from ApplicationException and SystemException.

public class LoggedException : SystemException
{
public LoggedException() : base()
{
}

public LoggedException(String message) : base (message)
{
}

public LoggedException(String message, Exception objInner) : base(message,
objInner)
{
}

public LoggedException(SerializationInfo srlInfo, StreamingContext
strmCntxt) : base(srlInfo, strmCntxt)
{
}
}

Now , I write the following code that raises SystemException, where obj is
still not allocated.Now my question is why it doesn't get caught in my catch
block, when my class is derived from SystemException.I have tried deriving
from Exception base class, but no use.How should I go about it, if I want to
access the protected member hresult of the exception class.
try
{
obj.GetType()
}
catch(LoggedException e)
{
//...........
}

[Maqsood Ahmed]

It is happening because you have derived LoggedException from
SystemException class. You can not deal with SystemException exception
in any of its devired class catch block. But its OK vice versa i-e
dealing with LoggedException inside SystemException's catch block.

Maqsood Ahmed [MCP,C#]
Kolachi Advanced Technologies
http://www.kolachi.net

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[Rahul Anand]

Hi Jasleen,

You can not catch a System.Exception type exception under a LoggedException
catch block. In any case you can catch the System.Exception and raise your
own exception in the catch block.

<CODE>

try
{
obj.GetType()
}
catch(Exception)
{
raise new LoggedEsception();
}
catch(LoggedException e)
{
//...........
}

</CODE>

Hope it will help....

Cheers,
Rahul Anand

"Jasleen" wrote:

I want to access the protected member hresult of the Exception class, so I
derived my own class from ApplicationException and SystemException.

public class LoggedException : SystemException
{
public LoggedException() : base()
{
}

public LoggedException(String message) : base (message)
{
}

public LoggedException(String message, Exception objInner) : base(message,
objInner)
{
}

public LoggedException(SerializationInfo srlInfo, StreamingContext
strmCntxt) : base(srlInfo, strmCntxt)
{
}
}

Now , I write the following code that raises SystemException, where obj is
still not allocated.Now my question is why it doesn't get caught in my catch
block, when my class is derived from SystemException.I have tried deriving
from Exception base class, but no use.How should I go about it, if I want to
access the protected member hresult of the exception class.
try
{
obj.GetType()
}
catch(LoggedException e)
{
//...........
}

[David Levine]

As Masqsood pointed out you cannot extend a base class and catch the derived
class's type instead of the base class's type. This is because the exception
that is thrown is the base type, not the extended type, and catch clauses
evaluate the exception and its base class, not its derived class.

However, what you can do is use reflection to access this normally
inaccessible field. A routine like this ought to do it...

private int GetHresult(Exception ex)
{
PropertyInfo pi =
ex.GetType().GetProperty("HResult",BindingFlags.In stance |
BindingFlags.NonPublic);
return (int)pi.GetValue(ex,null);
}

so in your catch handler you can do this...

try
{
obj.GetType(); // why this throws nobody knows....
}
catch(Exception e) // you really ought to catch a more specific type here.
{
int hr = GetHresult(ex);
// party on with the hresult value....
}
"Jasleen" <Ja*****@discussions.microsoft.com> wrote in message
news:A4**********************************@microsof t.com...

I want to access the protected member hresult of the Exception class, so I
derived my own class from ApplicationException and SystemException.

public class LoggedException : SystemException
{
public LoggedException() : base()
{
}

public LoggedException(String message) : base (message)
{
}

public LoggedException(String message, Exception objInner) :
base(message,
objInner)
{
}

public LoggedException(SerializationInfo srlInfo, StreamingContext
strmCntxt) : base(srlInfo, strmCntxt)
{
}
}

Now , I write the following code that raises SystemException, where obj is
still not allocated.Now my question is why it doesn't get caught in my
catch
block, when my class is derived from SystemException.I have tried deriving
from Exception base class, but no use.How should I go about it, if I want
to
access the protected member hresult of the exception class.
try
{
obj.GetType()
}
catch(LoggedException e)
{
//...........
}