Re: [Cdk-devel] Exceptions in cdk

[<we...@in...>]

Hello Stefan,

just an idea/comment !;-)

If Exceptions are used; every other method calling this method must have 
a try/catch-block which is a lot of work and slows down the processing 
time because simple return values would be faster. I want only to bear 
that in mind !
I think a simple return Double.NaN should work and every calling 
function can check this by
double hose=predict(hcode);
if(Double.isNaN(hose))
{
   logger.error(...)
   // or
   throw CDKException("Hose code "+hcode+" doesn't exist.")
   // or forward NaN
   return hose;
}
else
{
   // all is fine
}

C is not that bad and to return a register value will be always faster 
than returning a thread based Exception.

Regards, Joerg

> in general i think:
> - Exception should only be used if some weird things happening and
>    there is no developer possibility to avoid this, e.g. NullPointer,
>    NumberFormat, IO
> - they should not be to specific, because this causes overhead
> - they are usefull, if different exceptions can occure and the
>    developer wants to catch only a specific kind of exception.
>    BUT it's not a good idea to use Exception in general as return
>    value of methods if something weird is happening. Often a simple
>    true/false will work. If the why 'failed this method' is important
>    there exists still the logging with different modes.
> 
> 
> Hi Joerg,
> what you say sounds reasonable, but for me it seems to be more  C rather than 
> Java style. Take the BremserBlaBla methods:
> 
> 	public double predict(String hoseCode) throws CDKException
> 	{
> 		if (ht.containsKey(hoseCode))
> 		{
> 			return ((HOSECodeShiftRange)ht.get(hoseCode)).shift;
> 		}
> 		throw new CDKException("No such HOSE code");
> 
> The return type to indicate a failure would be, I suppose, a negative value 
> like -1. But this would be contrary to what you read in all the java books 
> and also to my own feeling (although I got that from the books, I admit). So 
> I think some sort of exception would be better.
> Stefan
> 


-- 
Dipl. Chem. Joerg K. Wegner
Univ. Tuebingen, Computer Architecture, Sand 1, D-72076 Tuebingen, Germany
Tel. (+49/0) 7071 29 78970, Fax (+49/0) 7071 29 5091
E-Mail: mailto:we...@in...
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