Use an alternative implementation of a FRuleEngineI

[Sébastien Boulet]

Hi all,

i would like to use an alternative implementation of the FRuleEngineI. My 
problem is that the FRuleEngineI is instantiated directly from two locations :
in com.hp.hpl.jena.reasoner.rulesys.FBRuleInfGraph
    @Override
    protected void instantiateRuleEngine(List<Rule> rules) {
        if (rules != null) {
            if (useRETE) {
                engine = new RETEEngine(this, rules);
            } else {
                engine = new FRuleEngine(this, rules);
            }
        } else {
            if (useRETE) {
                engine = new RETEEngine(this);
            } else {
                engine = new FRuleEngine(this);
            }
        }
    }
and in com.hp.hpl.jena.reasoner.rulesys.RETERuleInfGraph

    @Override
    protected void instantiateRuleEngine(List<Rule> rules) {
        if (rules != null) {
            engine = new RETEEngine(this, rules);
        } else {
            engine = new RETEEngine(this);
        }
    }

For now, if i want to use another FRuleEngineI, i have to sub class theses 
classes for instantiating my own FRuleEngineI implementation. And since theses 
classes (FBRuleInfGraph, RETERuleInfGraph) are instantiated directly by others 
ones (GenericRuleReasoner, FBRuleReasoner, OWLFBRuleReasoner…), i will have to 
sub class a lot of existing classes.

So my question is, is there an easiest way to do this ?

If not, i was thinking of introducing a singleton FRuleEngineIFactory (I kept 
the useRETE  flag for backward compatibility.) : 

public class FRuleEngineIFactory {
    private static FRuleEngineIFactory instance;
    public static void setInstance(FRuleEngineIFactory instance) { 
FRuleEngineIFactory.instance = instance; }
    public FRuleEngineIFactory getInstance() { return instance; }
    
    public FRuleEngineI createFRuleEngineI(ForwardRuleInfGraphI parent, 
List<Rule> rules, boolean useRETE) {
        FRuleEngineI engine;
        if (rules != null) {
            if (useRETE) {
                engine = new RETEEngine(parent, rules);
            } else {
                engine = new FRuleEngine(parent, rules);
            }
        } else {
            if (useRETE) {
                engine = new RETEEngine(parent);
            } else {
                engine = new FRuleEngine(parent);
            }
        }
        return engine;
    }
}

This factory might be used by

com.hp.hpl.jena.reasoner.rulesys.FBRuleInfGraph
    @Override
    protected void instantiateRuleEngine(List<Rule> rules) {
        engine = FRuleEngineIFactory.getInstance().createFRuleEngineI(this, 
rules, useRETE);
    }

and by com.hp.hpl.jena.reasoner.rulesys.RETERuleInfGraph
    @Override
    protected void instantiateRuleEngine(List<Rule> rules) {
        engine = FRuleEngineIFactory.getInstance().createFRuleEngineI(this, 
rules, true);
    }

And i could replace the factory instance by my own instance :

        FRuleEngineIFactory.setInstance(new CustomFRuleEngineIFactory());


What do you think of that ?

Regards,

Seb


: : . . . . . . . . . . . . . . . . . . . . . . . . . . : :
Sébastien Boulet
Lead développeur

intactile DESIGN
: : Création d’interfaces subtiles : :
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