Re: [rules-users] Adding a custom operator to drools?

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(); } } _______________________________________________ rules-users mailing list rules-users(a)lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-users