[xwiki-devs] [proposal] Cancelable events and refactoring script macros

Hello, I'd like to refactor AbstractScriptMacro in order to be able to change script behavior in the future without fanout violations. Here is the plan emerged after several discussions with ThomasM: Introduce a notion of cancelable events. Such events can be canceled by the receiver (providing an optional reason), the actual canceling is performed by the sender. http://dev.xwiki.org/xwiki/bin/view/Design/CancelableEvents Send a cancelable event ScriptEvaluationStartsEvent in AbstractScriptMacro just before evaluating the script and a ScriptEvaluationFinishedEvent right after evaluation has finished (in finally block). Add the following 3 listeners to those events (into rendering.internal.macro.script) and move the corresponding code from AbstractScriptMacro there: ScriptClassLoaderHandlerListener * does class loader manipulations currently performed by AbstractScriptMacro#getClassLoader & Co PermissionCheckerListener * Aborts execution of scripts that need PR if the document is not saved with PR * To distinguish velocity and PR scripts, introduce a new interface PrivilegedScriptMacro extends ScriptMacro and let AbstractJSR223ScriptMacro implement it NestedScriptMacroValidatorListener * Replaces NestedScriptMacroValidator (ScriptMacroValidator component is removed completely) The refactoring will remove the following methods (breaks API): AbstractJSR223ScriptMacro: * protected boolean canExecuteScript() * public List execute(JSR223ScriptMacroParameters, String, MacroTransformationContext) AbstractScriptMacro: * protected boolean canHaveJarsParameters() * protected ClassLoader getClassLoader(String, ClassLoader) WDYT? Alex