[rules-users] setting globals in rule file

[Chris Richmond]

Great...

 

 

So, can I simply switch the dialect to not use MVEL?

 

Chris

 

 

 

  _____  

From: rules-users-bounces at lists.jboss.org
[mailto:rules-users-bounces at lists.jboss.org] On Behalf Of Wolfgang Laun
Sent: Wednesday, October 14, 2009 8:50 AM
To: Rules Users List
Subject: Re: [rules-users] setting globals in rule file

 

I've used functions with Drools 5, but not with MVEL. A recent thread seemed
to indicate a problem with MVEL for functions, though.

What you show of your code appears to be OK.

-W

On Wed, Oct 14, 2009 at 8:35 PM, Chris Richmond <crichmond at referentia.com>
wrote:

Yeah..more fun with functions.  I have the following function

function String getMyValue(){ return "value 1"; }

I have declared it at the top of the rule file right after all imports and
dialect statement but before any rules

<imports>
global Services services;
global String currentProfilie;

# setup dialect for the semantic code to be MVEL
dialect "mvel"


function String getMyValue(){ return "value 1"; }


I then try to call the function from another rule consequence as a test:

then
       System.err.println(getMapRouterAddress());
       <other statements which work fine>



Now as soon as I start up and the rule file is loaded, I get a null pointer
exception that isn't really helpful as it simpoly points to one of my own
external objects that references the session that failed to load.

I have tried using functions many times and never successfully done so.
How/where do I place a simple function like this and call it?

Thanks


Chris



________________________________________
From: rules-users-bounces at lists.jboss.org
[mailto:rules-users-bounces at lists.jboss.org] On Behalf Of Wolfgang Laun

Sent: Wednesday, October 14, 2009 8:15 AM

To: Rules Users List
Subject: Re: [rules-users] setting globals in rule file

You could let the "user" write some functions such as

function String parFoo(){ return "foo42"; }

and evaluate them in a rule firing with high priority on eval(true).

-W


2009/10/14 Chris Richmond <crichmond at referentia.com>
Hmm.
 
Well..I have this rule file and it seems like a darn convenient place to set
some configuration settings so the user could change them in the plain text
file.  Otherwise I have to implement another configuration settgin system
then feed that to th setGlobal.
 
Chris
 
________________________________________
From: rules-users-bounces at lists.jboss.org
[mailto:rules-users-bounces at lists.jboss.org] On Behalf Of Wolfgang Laun
Sent: Wednesday, October 14, 2009 7:50 AM
To: Rules Users List
Subject: Re: [rules-users] setting globals in rule file
 
No, globals can only be set by calling the WorkingMemory method
   wm.setGlobal(String name, Object value)

You could call this in a consequence (RHS), but it's usually not a good idea
to do so.

What do you want to achieve?

-W
2009/10/14 Chris Richmond <crichmond at referentia.com>
Shouldn't it be possible to set a global variable value within the rule file
itself at the top.  Something like?
 
 
global String deviceName = "myDevice";
 
 
 
I thought you could do that, but  consistently get an error saying  illegal
character '=' expected "("
 
Or something along those lines.
 
This is possible and that syntax should work, shouldn't it?
 
Thanks,
Chris

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