> Is there a way to remove a rule from the rulebase at runtime?

> I want to create a rules engine that is exposed as a webservice.
> Clients will post to /facts/assert to put a new fact into the working
> memory and will post to /facts/retract to remove a fact from the
> working memory.  I currently start my environment by creating a single
> engine and single rulebook:

> //happens on start:
> RULER_ENGINE = Ruleby::Core::Engine.new
> RULE_BOOK = SimpleRulebook.new(RULER_ENGINE)
> RULE_BOOK.rules //loads rules from external source

> In my facts controller I have something like this:

>  def assert
>    RULER_ENGINE.assert CoolObj.new(params[:obj])
>    RULER_ENGINE.match
>    render :nothing => true
>  end

>  def retract
>    GarbageManRules.new(RULER_ENGINE) do |rb|
>      rb.rule [CoolObj, :c, m.pk == params[:pk], m.type == params
> [:type]] do |v|
>        rb.retract(v[:c])
>      end
>    end
>    RULER_ENGINE.match
>    render :nothing => true
>  end

> My understanding is that when I add the rule to the rulebase..its
> there forever.  In my case its really a transient rule just used to
> remove something from the working memory and should be removed after
> that action. Am I maybe approaching this wrong?  Is there a way to
> remove this rule from the rulebase once I am done with it?

> In your case, I think you would be better served by creating a new
> class that you can write rules for retracting facts around.  Something
> like this:

> class Retractor
>   attr :class_to_retract
> end

> rule [CoolObj, :c, m.pk == params[:pk], m.type == params[:type]],
>            [Retractor, :r, m.class_to_retract = CoolObj] do |v|
>        retract(v[:c])
>        retract(v[:r])
> end

> The Retractor class could even contain the patterns you use to select
> the CoolObjs.  I hope this helps, please let me know if its not clear.

> Joe

> On Tue, Oct 27, 2009 at 3:21 PM, Jake Dempsey <angelo0...@gmail.com> wrote:

> > Is there a way to remove a rule from the rulebase at runtime?

> > I want to create a rules engine that is exposed as a webservice.
> > Clients will post to /facts/assert to put a new fact into the working
> > memory and will post to /facts/retract to remove a fact from the
> > working memory.  I currently start my environment by creating a single
> > engine and single rulebook:

> > //happens on start:
> > RULER_ENGINE = Ruleby::Core::Engine.new
> > RULE_BOOK = SimpleRulebook.new(RULER_ENGINE)
> > RULE_BOOK.rules //loads rules from external source

> > In my facts controller I have something like this:

> >  def assert
> >    RULER_ENGINE.assert CoolObj.new(params[:obj])
> >    RULER_ENGINE.match
> >    render :nothing => true
> >  end

> >  def retract
> >    GarbageManRules.new(RULER_ENGINE) do |rb|
> >      rb.rule [CoolObj, :c, m.pk == params[:pk], m.type == params
> > [:type]] do |v|
> >        rb.retract(v[:c])
> >      end
> >    end
> >    RULER_ENGINE.match
> >    render :nothing => true
> >  end

> > My understanding is that when I add the rule to the rulebase..its
> > there forever.  In my case its really a transient rule just used to
> > remove something from the working memory and should be removed after
> > that action. Am I maybe approaching this wrong?  Is there a way to
> > remove this rule from the rulebase once I am done with it?