[rules-users] Benefits of pluggable operators

[Thomas Grayson]

What are the benefits of using pluggable operators (implementations of org.drools.base.evaluators.EvaluatorDefinition such str, matches, or before) versus simply making an equivalent function call?  I've read the Creating pluggable operators<http://blog.athico.com/2010/06/creating-pluggable-oprators.html> blog post.  Apart from saying that the Eclipse plugin can recognize these operators, it doesn't really make a case for why I'd want to create my own implementation.  One might argue that operators enhance reusability, but a static method offers much the same benefit.  Does a pluggable operator have any optimization, caching, or other advantage?

For example, here are two ways to match the start of a string in a property of a fact, one using  the "str[startsWith]" operator and another with Java's String.startsWith method:

declare Fact
    key : String @key
end

rule "Use operator"
    when
        Fact(key str[startsWith] "abc")
    then
        // do something
end

rule "Use method"
    when
        Fact(key.startsWith("abc"))
    then
        // do something
end

Does one of these perform better than the other?

Best wishes,
Tom

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