Hi Edson,

I think I got it working :-)

Edson Tirelli wrote:
> For an example, look at the file SetEvaluatorsDefinition and look at
> the BaseMemberOf inner class. So, all the logic is in there, but we
> still used subclasses just to set the constructor attributes and
> override the toString() method, but you could still implement
> everything in a single class I guess.

Yes, this approach makes sense as long as you don't need to use the
different VariableContextEntry subclasses for handling double, char etc.
Yet, this can be handled, too.

toString():
You can avoid subclassing from your BaseMyEvaluatorClass to override
toString() by using a string method like:

public String toString() {
 return getValueType().getName() + " " +
        getOperator().getOperatorString();
}

Regarding the evaluator API:
If you only need one evaluator class (subclassed from BaseEvaluator),
personally I don't like the > 10 static calls to
   addEvaluator(type, operator, myEvaluatorInstance)
in the EvaluatorDefinition class.

So, how about adding the method addDefaultEvaluator(operator,
evaluatorClass) to EvaluatorCache, see attachment?
This would allow you to register a evaluator as default and only overide
the special cases...


PS: If you are interested I will write some small tutorial about custom
evaluators / operators in drools trunk. This might take a week or two,
though. Any preferences regarding the format?

Thanks for the help....

cu, Michael


@SuppressWarnings("unchecked")
public void addDefaultEvaluator(final Operator operator, Class evaluatorClass) {
// define the constructor
Class[] evaluatorParameters = new Class[2];
evaluatorParameters[0] = ValueType.class;
evaluatorParameters[1] = Operator.class;

// get the constructor
       try {
       Constructor<BaseEvaluator> constructor;
               constructor = evaluatorClass.getConstructor( evaluatorParameters );

               // add feault operators
       addEvaluator(ValueType.ARRAY_TYPE, operator, constructor.newInstance(ValueType.ARRAY_TYPE, operator));
       addEvaluator(ValueType.BIG_DECIMAL_TYPE, operator, constructor.newInstance(ValueType.BIG_DECIMAL_TYPE, operator));
       addEvaluator(ValueType.BIG_INTEGER_TYPE, operator, constructor.newInstance(ValueType.BIG_INTEGER_TYPE, operator));
       addEvaluator(ValueType.BOOLEAN_TYPE, operator, constructor.newInstance(ValueType.BOOLEAN_TYPE, operator));
       addEvaluator(ValueType.PBOOLEAN_TYPE, operator, constructor.newInstance(ValueType.PBOOLEAN_TYPE, operator));
       addEvaluator(ValueType.BYTE_TYPE, operator, constructor.newInstance(ValueType.BYTE_TYPE, operator));
       addEvaluator(ValueType.PBYTE_TYPE, operator, constructor.newInstance(ValueType.PBYTE_TYPE, operator));
       addEvaluator(ValueType.CHAR_TYPE, operator, constructor.newInstance(ValueType.CHAR_TYPE, operator));
       addEvaluator(ValueType.PCHAR_TYPE, operator, constructor.newInstance(ValueType.PCHAR_TYPE, operator));
       addEvaluator(ValueType.DATE_TYPE, operator, constructor.newInstance(ValueType.DATE_TYPE, operator));
       addEvaluator(ValueType.DOUBLE_TYPE, operator, constructor.newInstance(ValueType.DOUBLE_TYPE, operator));
       addEvaluator(ValueType.PDOUBLE_TYPE, operator, constructor.newInstance(ValueType.PDOUBLE_TYPE, operator));
       addEvaluator(ValueType.FLOAT_TYPE, operator, constructor.newInstance(ValueType.FLOAT_TYPE , operator));
       addEvaluator(ValueType.PFLOAT_TYPE, operator, constructor.newInstance(ValueType.PFLOAT_TYPE, operator));
       addEvaluator(ValueType.INTEGER_TYPE, operator, constructor.newInstance(ValueType.INTEGER_TYPE, operator));
       addEvaluator(ValueType.PINTEGER_TYPE, operator, constructor.newInstance(ValueType.PINTEGER_TYPE, operator));
       addEvaluator(ValueType.LONG_TYPE, operator, constructor.newInstance(ValueType.LONG_TYPE, operator));
       addEvaluator(ValueType.PLONG_TYPE, operator, constructor.newInstance(ValueType.PLONG_TYPE, operator));
       addEvaluator(ValueType.OBJECT_TYPE, operator, constructor.newInstance(ValueType.OBJECT_TYPE, operator));
       addEvaluator(ValueType.SHORT_TYPE, operator, constructor.newInstance(ValueType.SHORT_TYPE, operator));
       addEvaluator(ValueType.PSHORT_TYPE, operator, constructor.newInstance(ValueType.PSHORT_TYPE, operator));
       addEvaluator(ValueType.STRING_TYPE, operator, constructor.newInstance(ValueType.STRING_TYPE, operator));
       } catch (SecurityException e) {
               // TODO Auto-generated catch block
               e.printStackTrace();
       } catch (NoSuchMethodException e) {
               // TODO Auto-generated catch block
               e.printStackTrace();
       } catch (IllegalArgumentException e) {
               // TODO Auto-generated catch block
               e.printStackTrace();
       } catch (InstantiationException e) {
               // TODO Auto-generated catch block
               e.printStackTrace();
       } catch (IllegalAccessException e) {
               // TODO Auto-generated catch block
               e.printStackTrace();
       } catch (InvocationTargetException e) {
               // TODO Auto-generated catch block
               e.printStackTrace();
       }
}

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