Exception handling and debugging
To handle errors, you use the error
codes returned from PBNI methods. Some functions of the IPB_Session
interface return detailed error codes that make debugging easier.
Native methods, such as the IPBX_UserObject Invoke method,
return either PBX_OK or PBX_FAIL if the extension
encounters a serious problem from which it cannot recover.
Whenever the PowerBuilder VM gets PBX_FAIL from a
native method, it throws a PBXRuntimeError in the PowerBuilder application. PBXRuntimeError
inherits from the PowerBuilder RuntimeError system object and can
be caught and handled in a script in the same way as any exception
in PowerBuilder.
To catch these errors, wrap your PowerScript call in a try-catch
block as follows:
|
1 |
TRY<br>   n_cpp_pbniobj obj<br>   obj = CREATE n_cpp_pbniobj<br>   obj.of_test( arg1 )<br>CATCH ( PBXRuntimeError re )<br>   MessageBox( "Caught error", re.getMessage() )<br>END TRY |
The
IPB_Session interface provides a set of methods to handle
exceptions that occur in native code. Use HasExceptionThrown to
determine whether an exception occurred. If it did, use GetException to
get the current exception object so that it can be handled. If necessary,
you can throw exceptions to PowerBuilder with ThrowException.
When an exception has been handled, use ClearException to clear it.
Debugging
You cannot edit a native class in the PowerBuilder development
environment, and you cannot enter native methods in the PowerBuilder
debugger because the methods are C++ methods.
You must use a C/C++ debugger to debug
an extension module.