Textual Rules: evaluate global variables in the context of previous variables

[dilyanpalauzov]

Before this change openhab/rules/b.rules:

val a = 1
val b = a + 2

rule "B"
when Item b changed
then 
  logError("B", Integer.toString(b))
end

emitted

[INFO ] [el.core.internal.ModelRepositoryImpl] - Loading DSL model 'b.rules'
[WARN ] [e.runtime.internal.RuleContextHelper] - Variable 'b' on rule file 'b.rules' cannot be initialized with value '<XFeatureCallImplCustom> + <XNumberLiteralImpl>': An error occurred during the script execution: Could not invoke method: org.eclipse.xtext.xbase.lib.IntegerExtensions.operator_plus(int,int) on instance: null

and during execution

[ERROR] [.handler.AbstractScriptModuleHandler] - Script execution of rule with UID 'b-1' failed: An error occurred during the script execution: Could not invoke method: java.lang.Integer.toString(int) on instance: null in b

With the current change the above produces:

[INFO ] [el.core.internal.ModelRepositoryImpl] - Loading DSL model 'b.rules'
[ERROR] [org.openhab.core.model.script.B     ] - 3

Closes: #3696
Closes: #4493.

[dilyanpalauzov]

This also works as expected:

val lock = new java.util.concurrent.locks.ReentrantLock
var a = 1
val ()=>String b = [
  lock.lock
  a++
  lock.unlock
  Integer.toString(a)
]

rule "B1"
when Item b changed
then
  logError("B1", b.apply)
end

rule "B2"
when Item b changed
then
  logError("B2", b.apply)
end

[holgerfriedrich]

Why do you remove getVariableDeclaration? I can't find where it is used, but do I overlook any specific reason why it needs to be removed.....

[dilyanpalauzov]

The only usage of RuleContextHelper is:

$ git grep -n RuleContextHelper
bundles/org.openhab.core.model.rule.runtime/src/org/openhab/core/model/rule/runtime/internal/DSLRuleProvider.java:214: IEvaluationContext context = RuleContextHelper.getContext(ruleModel);
bundles/org.openhab.core.model.rule.runtime/src/org/openhab/core/model/rule/runtime/internal/RuleContextHelper.java:36:public class RuleContextHelper {
bundles/org.openhab.core.model.rule.runtime/src/org/openhab/core/model/rule/runtime/internal/RuleContextHelper.java:47:Logger logger = LoggerFactory.getLogger(RuleContextHelper.class);

The method RuleContextHelper.getVariableDeclaration() is deleted, because it is not called from anywhere.