The Builder

Build à la carte rules and rule books without a dedicated class.

The Builder

Builder@rulebox is a singleton that lets you create rules and rule books on the fly, without writing a dedicated class that extends RuleBook.

When to use it: use the Builder when the rules are put together at runtime (from user choices, settings, or a database). Use a RuleBook class when the rules are fixed, so you can name, reuse and test them.

Inject it into any class:

class singleton{

	property name="builder" inject="Builder@rulebox";

	function greet( name ){
		return builder.rulebook( "Greeter" )
			.addRule(
				builder.rule()
					.then( ( facts, result ) => result.setValue( "Hello " & facts.name ) )
			)
			.addRule(
				builder.rule()
					.then( ( facts, result ) => result.setValue( result.getValue() & "!" ) )
			)
			.run( { name : arguments.name } )
			.getResult()
			.getValue()
	}

}

Outside of WireBox-managed classes, ask for it with getInstance( "Builder@rulebox" ).

Since builder.rulebook() returns a normal RuleBook instance, every method described in The RuleBook DSL and Facts & Results - given(), withDefaultResult(), addRule(), run() - is available on it, exactly as it would be on a hand-written RuleBook subclass.

If your rules live in JSON, YAML, or a database, see Externalized Rule Definitions. loadRules() works on a Builder rulebook too.