Extend ExceptionHandler to allow user defined exceptions and exception tagging

Created by: wgurecky

This is a proposed enhancement of ExceptionHandler to allow the registration of user defined exception types derived from a base exception type.

Benefits

• Usability: allow client code to handle an unlimited variety of exceptions without having to interrogate the log file or look at the lastMesg string.
• Code organization: place logic regarding error message generation into the user exception type.

Proposed Design

Module ExceptionHandler

ExceptionHandlerType

Attributes

• Remove: nError, nWarning, ect. verbose, quiet
• New: exceptionRegistry - contains user defined exceptions.
• New: isInit - bool flag

Methods

• New method: init() - Fill the exceptionRegistry with the 5 default exception types.
• New method: registerException(e,userExcept) - enforce unique tags
• New method: raise(e,userExcept,msg) or raise(e,tag,msg)
• New method: getErrorCountByType(e,userExcept) or getErrorCountByTag(e,tag)
• Remove: logMessage
• Remove: exceptionStop
• Redef: raiseError, raiseWarning, ect become aliases to the more general raise method.

Notes:

• Enforce that init() is called before using the exception handler.
• Keep all existing functionality for legacy support. All existing ExceptionHandler tests should pass.
• Unresolved: how to safely copy from surrogate and defer raises to surrogate.

Module ExceptionType

ExceptionTypeBase

Attributes

• tag - integer, unique id of exception type
• counter - integer
• quiet - bool flag
• verbose - bool flag
• stopmode - bool flag

Methods

• init(tag)
• onRaise(isQuiet, isLogActive,logUnit,mesg)
• getCount, setCount, getQuiet, setQuiet, getVerbose, setVerbose
• logMessage(isQuiet, isLogActive,logUnit,mesg)

Virtual

• genPrefix

Module (non Type-bound)

• exceptionStop(stopmode)

ExceptionTypeError,extends(ExceptionTypeBase)

• genPrefix() -> "#### EXCEPTION_ERROR ####"