Rethrowing Exceptions
You might want your
catch
block to take some initial corrective action
and then rethrow the exception to an outer try
block (in a calling function). It might rethrow the
same exception, or it might throw a different
one. If it throws a different one, it may want to embed the original
exception inside the new one so that the calling method can
understand the exception history. The
InnerException
property of the new exception
retrieves the original exception.
Because the InnerException
is also an exception,
it too might have an inner exception. Thus, an entire chain of
exceptions can be nested one within the other, much like Ukrainian
dolls are contained one within the other. Example 11-8 illustrates.
Example 11-8. Rethrowing inner exceptions
namespace Programming_CSharp { using System; public class MyCustomException : System.ApplicationException { public MyCustomException( string message,Exception inner): base(message,inner) { } } public class Test { public static void Main( ) { Test t = new Test( ); t.TestFunc( ); } public void TestFunc( ) { try { DangerousFunc1( ); } // if you catch a custom exception // print the exception history catch (MyCustomException e) { Console.WriteLine("\n{0}", e.Message); Console.WriteLine( "Retrieving exception history..."); Exception inner = e.InnerException; while (inner != null) { Console.WriteLine( "{0}",inner.Message); inner = inner.InnerException; } } } public void DangerousFunc1( ) { try { DangerousFunc2( ); } // if you ...
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