[rules-users] setting globals in rule file

[Wolfgang Laun]

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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