[rules-users] Setting a value in LHS

[Davide Sottara]

The usual (and only reasonable way) to "set" a variable in the LHS is to
bind it to a Drools variable,
including things like:

...
$x : String() from /* expression here */
...

any usage of the "=" operator is generally suspicious..
but I'm not sure I have understood your use case completely.. :)



On 06/04/2013 05:59 PM, Stephen Masters wrote:
> Thanks for the cheat idea Mike. I wasn't really expecting any help
> from the tooling itself. Just hoping that there might be some trickery
> within the DSL that I could try, to generate some code which would set
> up a variable for me.
>
> Unfortunately I do need to combine LHS sentences and multiple RHS
> sentences, so your idea isn't really an option in this case. :(
>
> As it is I have created a little enumeration in the RHS sentence, and
> it's not looking too bad. At least, with some selective wording, it
> doesn't look completely redundant!
>
> Steve
>
>
>
> On 4 Jun 2013, at 16:33, Michael Anstis <michael.anstis at gmail.com
> <mailto:michael.anstis at gmail.com>> wrote:
>
>> This would need to be provided by the tooling; I don't think it's
>> something that's even remotely possible at runtime (unless you stored
>> the field name in a Fact and used reflection on the RHS).
>>
>> That said (and you're going to guess my next comment) this is not
>> provided in the guided editors. Depending on how complex your DSLs
>> are and whether users need to combine DSL Sentences; IDK if a "cheat"
>> works:
>>
>> [when]Do something with {field} and {value}=$f :
>> Fact({field}=={value} then $f.{field} = {value}
>>
>> I've not tried it; nor know whether it fits your requirements.. but a
>> hack worth trying?
>>
>>
>> On 3 June 2013 17:40, stephen.masters <stephen.masters at me.com
>> <mailto:stephen.masters at me.com>> wrote:
>>
>>     Hi folks,
>>
>>     Is there a decent way to set a value in the LHS of a rule so that
>>     it's available in the RHS?
>>
>>     Reason being I have a DSL driving the guided rules editor which
>>     will pluck out the value of a field, where the name of that field
>>     is driven by a drop down menu enumeration.
>>
>>     A change I now have would be a lot easier if I could assign a
>>     string to a variable in the LHS, which could be read by the RHS.
>>     Otherwise I might need to extend the RHS DSLs to include the same
>>     enumeration as the LHS. Which looks a bit redundant for a
>>     business user wondering why the need to write the same thing twice.
>>
>>     Any thoughts?
>>
>>     Steve
>>
>>
>>
>>
>>     Sent from Samsung Mobile
>>
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>>
>>
>
>
>
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