Re: values for fields in failure/exception

From: (Stefan Ram)
10 Dec 2010 05:50:56 GMT
mark jason <> writes:

In my program , I am returning a MyResult instance containing values
from a calculation.If an exception occurs ,I would like to return the
object with values which represent a failed calculation .The problem
is that,I cannot put distance as 0.0 since it is one of the valid
distance values.

  The purely object-oriented solution is as follows:

calculate( expression, success, failure );

  . ?calculate? does the calculation based on the object
  ?expression? and then calls the ?acceptResult? method of the
  object ?success? if the calculation was a success or the
  ?acceptFailure? method of the object ?failure? if the
  calculation failed.

  A partially object-oriented solution is as follows:

interface Result {};
class SuccessResult implements Result { /* result data here */ };
final Result result = calculate();
if( result instanceof SuccessResult )
{ final SuccessResult successResult =( SuccessResult)result;
  /* use data here */ }
{ /* error handling */ }

  Another solution uses exceptions:

{ final Result result = calculate();
  /* use data here */ }
catch( final CouldNotCalculateException couldNotCalculateException )
{ /* error handling */ }

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