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[ANN] BDRuleEngine 1.0.0 released

I figured some of the people here might be interested, since using a rule system might make development of certain types of games easier. And if anyone has any suggestions or comments, I'd love to hear them.

I just shipped BDRuleEngine version 1.0.0, an Open Source framework that provides Cocoa developers with the ability to develop business rule-driven applications. BDRuleEngine requires BDControl 1.0.3 or later, another Open Source framework I released a couple weeks ago.

I also shipped a simple application for editing rule sets, BDRuleEditor. BDRuleEditor requires BDRuleEngine 1.0.0 or later and BDControl 1.0.3 or later.

BDRuleEngine: http://bdistributed.com/Projects/BDRuleEngine/
BDRuleEditor: http://bdistributed.com/Projects/BDRuleEditor/
BDControl: http://bdistributed.com/Projects/BDControl/

The rule system works by letting you specify rules, supply some initial data in a context connected to those rules, and then ask that context various questions about that data.

Rules have the form

(condition) => keyPath = value [priority]

where "condition" is a qualifier object. (See the description of BDQualifier in the BDControl documentation for details; in short, qualifiers are object-oriented predicates.)

For instance, a couple rules for an adventure game might include:

(torch.burning = NO)
=> exitsVisible = () [100]

(torch.burning = NO)
=> description = "Your torch is out. You can't see a thing." [100]

((room.name = 'mainHall') and (torch.burning = YES))
=> exitsVisible = ("north", "south", "west") [100]

((room.name = 'mainHall') and (exit = 'north'))
=> description = "There is a door to the north." [100]

((room.name = 'mainHall') and (exit = 'north') and (exit.open = YES))
=> description = "There is an open door to the north." [100]

To start with, you'd create a context linked to the above rules and set whatever data you needed. For instance, you'd set the context's "torch" key to your torch object. Then you ask the context for a value, such as "description". When you ask for that key, the rule system finds the most applicable rule given all of the data in your context that has that key on the right hand side of the "=>", and returns the value for that key.

Thus if your torch is initially not burning, asking the context for the value of the exitsVisible key would return an empty array, and asking for the value of the "description" key would return "Your torch is out. You can't see a thing." regardless of what room you're in. When you turn your torch on, asking the context for the value of either key will instead return the appropriate value depending on the name of the room you're currently in.

Priorities are used to differentiate among equally-applicable rules; the rule with the higher priority is the one that's fired.

BDRuleEngine uses Objective-C's introspection features via the key-value coding mechanism to work its magic, so you don't need to do anything special in your own classes to be able to use them with the rule system.

-- Chris

--
Chris Hanson | Email: email@hidden
bDistributed.com, Inc. | Phone: +1-847-372-3955
Making Business Distributed | Fax: +1-847-589-3738
http://bdistributed.com/ | Personal Email: email@hidden
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