The globals are global to the consequence, where we inject them for the user. For the function we expect the user to pass those injected globals as arguments, i'm not convinced that this is overly more painful that the variables automatigically being there in the function.

That said if someone was will doing to do the work, we woudl probably accept the patch. But it would need to do the following.
1) determine the used globals for the function
2) add those parameters onto the end of the generated function.
3) update any generated consequences, or functions for that matter, and add in the globals to the paramters list.

So basically a lot of data munging in the templates.

Mark
Greg Barton wrote:

How about a ThreadLocal?

--- On Wed, 10/15/08, David Sinclair <dsinclair@chariotsolutions.com> wrote:

  

From: David Sinclair <dsinclair@chariotsolutions.com>
Subject: [rules-dev] Re: [rules-users] No globals in functions?
To: "Edson Tirelli" <tirelli@post.com>
Cc: "Mark Proctor" <mproctor@codehaus.org>, "Rules Dev List" <rules-dev@lists.jboss.org>
Date: Wednesday, October 15, 2008, 12:53 PM
What about injecting the globals into the classes and doing
reflection to
invoke the method dynamically? That way we would only need
to change the
JavaFunctionBuilder to rewrite the calls to the globals?
For example

function foo() {
    global.bar(abx);
}

gets re-written as

function foo() {
     method.invoke(global, [abx]);
}

methods would be cached and such. Or do you guys not want
the reflection in
there?


On Wed, Oct 15, 2008 at 1:45 PM, Edson Tirelli
<tirelli@post.com> wrote:

    

   It may be invoked by a consequence, an eval, a
      

predicate, or a return
    

value constraint.

   If you fix it for the consequence in
      

JavaConsequenceBuilder, the others
    

will work the same. You will have to change the java.g
      

grammar as I
    

mentioned in my previousre e-mail to make it work.

   []s
   Edson

2008/10/14 David Sinclair
      

<dsinclair@chariotsolutions.com>
    

 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@post.com> 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@chariotsolutions.com>
    

 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@sandia.gov>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@lists.jboss.org [mailto:
    

rules-users-bounces@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@sandia.gov>
    

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@sandia.gov
phone:  505/284-4517
fax:  505/ 844-7886

There is no monument dedicated to
                

the memory of a committee. -- Lester
    

J. Pourciau





                

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--
 Edson Tirelli
 JBoss Drools Core Development
 JBoss, a division of Red Hat @
              

www.jboss.com
    

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--
 Edson Tirelli
 JBoss Drools Core Development
 JBoss, a division of Red Hat @ www.jboss.com

          

--
 Edson Tirelli
 JBoss Drools Core Development
 JBoss, a division of Red Hat @ www.jboss.com

      

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