[rules-users] Support for dynamic / ad-hoc queries in Drools

[Wolfgang Laun]

On 27 June 2012 16:20, Swindells, Thomas <TSwindells at nds.com> wrote:

>
>
> > -----Original Message-----
> > From: rules-users-bounces at lists.jboss.org [mailto:rules-users-
> > bounces at lists.jboss.org] On Behalf Of Wolfgang Laun
> > Sent: 27 June 2012 14:47
> > To: Rules Users List
> > Subject: Re: [rules-users] Support for dynamic / ad-hoc queries in Drools
> >
> > On 27/06/2012, jpullmann <jaroslav.pullmann at fit.fraunhofer.de> wrote:
> > >  Hello Wolfgang,
> > >
> > >  the suggested solution is an elegant syntactical shortcut to what I
> > > and other Drools users already do. Support for one-shot queries
> > > appears  to be a meaningful extension to the WorkingMemory API, and
> > > the unavoidable
> > >
> > >  effort of parsing and temporarily adding the query pattern to the
> > > production  memory will become transparent to the user.
> >
> > There is still to be decided what to do when compilation fails - throw an
> > Exception or return null (with a factory method rather than a
> constructor).
>
> If there is any chance that null is a valid value to be returned (which I
> think there is?)


That's up to the implementor of the class I was outlining. Errors would
have to be logged somewhere.



> then it has to be an exception.
> Besides which it is nice to know why the compilation failed with a useful
> error message where possible.
>

This always depends on the application context, so the class might have to
cater for that. Hey, I was just drafting. ;-)

-W


> Thomas
>
>
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