Re: [rules-users] Instatiating Global Variables

I am having a few issues with Global Variables and was wondering if someone could possibly explain them to me..... I am coming from a CLIPS/JESS background where globals are very straight forward. ie (global ?*FAMILY_NAME* = "SMITH") and you can use it everywhere after that. You can declare them anywhere you want(ie outside/inside rules, inside a function call), use them whenever you want (within the LHS/RHS or in a function) and modify them whenever you want (although you shouldn't). In Drools however, they seem overly complicated. For instance.....I can't declare and initialize a global in the same line. IE you can't do this.... global String FAMILY_NAME = "SMITH"; Instead you have to just declare the global as.....global String FAMILY_NAME. Then after it's declared it can be set. Although for the life of me, setting it is not straight forward either. In a different thread on this list someone suggested doing the following....ie making sure the salience number is the highest of any rule forcing it to always fire first.... rule "Initialize Rule" salience 100 when eval(FAMILY_NAME == null); then WorkingMemory wm = drools.getWorkingMemory(); String familyName = "SMITH"; wm.setGlobal("FAMILY_NAME", familyName); System.out.println("FAMILY_NAME = " + FAMILY_NAME); end this does not seem to set the Global Variable value. The result is...FAMILY_NAME = null. and any other rule that I have in place that utilizes this global doesn't fire. ie rule "First Rule to Fire" when eval(FAMILY_NAME != null) then ..... end This never fires.... However, if through my java application (not in a DRL file), I call ......code..... workingMemory.setGlobal("FAMILY_NAME", familyName); fireAllRules(); ....more code.... then my "Firest Rule To Fire" rule fires as expected. There has to be something I am not fully understanding here because it doesn't seem right that I can't create and set the Global all in one step, or the fact that I can't set the variable value in a rule, but only through a java app. I also don't understand why the Globals can't be used directly by functions and why they have to be passed in as a variable to the function. If the function and the Global are defined within a specific working memory, then it should be available to all rules and functions within that same working memory. Similar to Java Class Member Data. The member data is available anywhere in that class. If anyone can help shed some light on the subject I would be very grateful! Joshua -- View this message in context: http://www.nabble.com/Instatiating-Global-Variables-tf4740897.html#a13556883 Sent from the drools - user mailing list archive at Nabble.com. _______________________________________________ rules-users mailing list rules-users(a)lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-users