[rules-dev] Re: [rules-users] No globals in functions?

Edson, Changing the builder shouldn't be too much of a problem. If I make the changes you suggested, how does the global actually get passed to the method? For example if something defined a function like void function doX(int abc) { ... global.doY(bcd); } and I rewrite it to be void function doX(int abc, GlobalType global) { ... } Who is the invoker of the method? thanks dave On Mon, Oct 13, 2008 at 3:24 PM, Edson Tirelli <tirelli(a)post.com&gt; wrote: > > Hi Dave, > > Excellent! > I will try to explain the current situation and one possible solution, > but you may have better ideas. > > Functions in Drools are compiled as simple static methods in a > generated java class. We use MVEL Templates to generate the code of the > class and the static method. > > Take a look at JavaFunctionBuilder.java class for the code generation > call and at javaFunction.mvel for the code template. > > Now, the problem with globals is that they are scoped to sessions, not > rulebases, so you can not resolve them until runtime. You can not for > instance, make them a static reference of the generated class and set it at > rulebase compilation time. > > So, my suggestion would be to: > > 1. at compile time, use JavaDialect.analyzeBlock() method to analyze and > find out what are the globals that are used by the funcion method code. > > 2. modify the code generation to add parameters to that in the method > call. So, if "log" is a global and if the function is declared like this: > > function void someFunction( String param ) { > // ... code ... > log.something(...); > // ... code ... > } > > you detect the use of "log" and add it as a parameter of the generated > method: > > ... > public static void someFunction( Logger log, String Param ) { > ... > } > ... > > This way, at runtime we can inject the parameter into the call. You can > look at JavaConsequenceBuilder.java and javaInvokers.mvel to see how we do > kind-of the same thing for consequences. > > 3. Now the most interesting part. :) We use an ANTLR grammar for parsing > Java code blocks. You need to change the parser to rewrite any function call > the user is doing in his code to inject the log parameter transparently. I > did the very same thing for modify blocks: > > modify( $something ) { > ... > } > > It is not hard once you get the hang of it. It is a bit of "hand work" > though. Look at the JavaConsequenceBuilder.fixModifyBlocks() for what I did. > Also, the ANTLR Java grammar is java.g. > > Let me know if you have questions or if you have a better idea, and > welcome aboard! > > Cheers, > Edson > > > > 2008/10/13 David Sinclair <dsinclair(a)chariotsolutions.com&gt; > > Hi Edson, >> >> My name is dave sinclair. I started using Drools in early August of this >> year, but have a lot of experience with rules engines. I have worked >> primarily with ArtEntrprise and some with PegaRules. I would love to help >> with this project and thought that this may be the area to jump in on. >> >> I have the M2 code, and was reading it over the weekend. Mostly the core >> and some of the compilier. If you want to point me in the right direction on >> the global/functions I'd be happy to have a look. >> >> thanks >> >> dave >> >> >> On Mon, Oct 13, 2008 at 9:59 AM, Bagwell, Allen F <afbagwe(a)sandia.gov&gt;wrote: >> >>> Edson, >>> >>> Thanks for the tip. I figured I'd need to use a workaround like this. >>> >>> Unfortunately I'm under a series of tight development and test deadlines >>> all the way into early summer. Otherwise, I'd have a look. Hopefully someone >>> else out there can assist. >>> >>> Thanks, >>> -A >>> >>> ------------------------------ >>> *From:* rules-users-bounces(a)lists.jboss.org [mailto: >>> rules-users-bounces(a)lists.jboss.org] *On Behalf Of *Edson Tirelli >>> *Sent:* Friday, October 10, 2008 5:46 AM >>> *To:* Rules Users List >>> *Subject:* Re: [rules-users] No globals in functions? >>> >>> >>> Allen, >>> >>> There is a technical explanation behind that and we never had the >>> time to find a way to overcome this limitation. What you can do, although >>> not ideal, is to send the global as a parameter: >>> >>> funcion void foo( Logger log, String cond ) >>> { >>> ... >>> } >>> >>> rule XYZ >>> when >>> then >>> foo( log, someString ); >>> end >>> >>> If you or anyone would like to help improving this, let us know and >>> we can discuss ways into doing it. >>> >>> []s >>> Edson >>> >>> 2008/10/9 Bagwell, Allen F <afbagwe(a)sandia.gov&gt; >>> >>>> >>>> There's probably an easy explanation for this. I was wondering about >>>> why functions inside of rule files can't access globals? >>>> >>>> For example, I have a log4j logger that I pass into my rule files via a >>>> global. The logger should never be a part of working memory. It's just >>>> there to capture valuable feedback. >>>> >>>> But I can't do this: >>>> >>>> global Logger log; >>>> >>>> function void foo(String cond) >>>> { >>>> if (cond == "error") >>>> log.error("I saw an error"); >>>> } >>>> >>>> Because the compiler says that in the function it can't resolve 'log'. >>>> >>>> -A >>>> >>>> Allen F. Bagwell >>>> e-mail: afbagwe(a)sandia.gov >>>> phone: 505/284-4517 >>>> fax: 505/ 844-7886 >>>> >>>> There is no monument dedicated to the memory of a committee. -- Lester >>>> J. Pourciau >>>> >>>> >>>> >>>> >>>> _______________________________________________ >>>> rules-users mailing list >>>> rules-users(a)lists.jboss.org >>>> https://lists.jboss.org/mailman/listinfo/rules-users >>>> >>>> >>> >>> >>> -- >>> Edson Tirelli >>> JBoss Drools Core Development >>> JBoss, a division of Red Hat @ www.jboss.com >>> >>> _______________________________________________ >>> rules-users mailing list >>> rules-users(a)lists.jboss.org >>> https://lists.jboss.org/mailman/listinfo/rules-users >>> >>> >> > > > -- > Edson Tirelli > JBoss Drools Core Development > JBoss, a division of Red Hat @ www.jboss.com >