Hi Johann, Sure! Here’s a hypothetical.
Let’s say I have a WorkflowRoutable interface that defines a few instance methods. Now I can implement that interface on EOs that need to participate in workflow, and call those methods in my workflow processing without any trouble. Now let’s say there’s some useful information used when configuring workflow queues to be able to handle a particular entity, but I may not have any instances at that point. I would want to define a class method as part of my WorkflowRoutable interface, so that I can safely call that method to get that entity-specific workflow information. Again, no problem in ObjC. But static methods can’t be in Java interfaces (at least in that way). Can the Clazz approach help with something like this? What I do see that I could do using the EOEnterpriseObjectClazz approach is implement the “class” method in the superclass of all my EOs with perhaps a default implementation that returns null. Then on my entities participating in workflow, they could override that method to return useful information. But now *all* of my classes have that default implementation, so it’s not really a clean workaround…. Thanks again! Mark From: Johann Werner <johann.wer...@posteo.de> Date: Tuesday, November 20, 2018 at 3:39 AM To: "Morris, Mark" <mark.mor...@experian.com> Cc: "Webobjects-dev@lists.apple.com" <Webobjects-dev@lists.apple.com> Subject: Re: EOEnterpriseObjectClazz with interface Hi Mark, I think you have to tell us what exactly you want to achieve? Do you have an example? With the EOEnterpriseObjectClazz you have a static instance within your class but this instance is… an instance so you could put an „implements interface“ on it. Or if you just want to know if class A has a static clazz object you could create some empty interface (IHasClazzObject) as marker. jw Am 19.11.2018 um 22:12 schrieb Morris, Mark <mark.mor...@experian.com<mailto:mark.mor...@experian.com>>: Hallo Johann, Thanks for the info. I do see how I could create a default implementation of the “static” method I’m expecting in our local EO superclass’s util inner class, and from then on know that it will be legal to call it from any of our subclasses. So that could work in this case. In general though I still don’t see how, or if it’s even possible, to do what I was originally trying with the interface. For instance methods, I can just test “myClass instanceof myInterface” and know whether that class implements the methods. In ObjC, I could do the same with a protocol, but with instance and class methods. It seems like the description of the clazz paradigm is saying it makes that possible, but I’m just not understanding how that works. Thanks again. Tschüß! Mark From: Johann Werner <johann.wer...@posteo.de<mailto:johann.wer...@posteo.de>> Date: Monday, November 19, 2018 at 1:37 AM To: "Morris, Mark" <mark.mor...@experian.com<mailto:mark.mor...@experian.com>> Cc: "Webobjects-dev@lists.apple.com<mailto:Webobjects-dev@lists.apple.com>" <Webobjects-dev@lists.apple.com<mailto:Webobjects-dev@lists.apple.com>> Subject: Re: EOEnterpriseObjectClazz with interface Hi Mark, have a look at BugTracker and its dependent framework BTBusinessLogic. That should you give some ideas. There are some more apps/frameworks in Wonder using that pattern, just have a look at the type hierarchy of the EOEnterpriseObjectClazz class (in Eclipse right click on the class name and select „Open Type Hierarchy“ from the context menu). jw Am 19.11.2018 um 06:31 schrieb Morris, Mark <mark.mor...@experian.com<mailto:mark.mor...@experian.com>>: Hi all, I ran into a simple case where a good old ObjC protocol would have worked fine, but Java provides only frustration. 😉 I wanted to require that a class that decides to implement a particular interface should as part of that interface implement a certain static method. No go in Java. The implementing classes will always be subclasses of ERXGenericRecord, and a little searching uncovered the promising EOEnterpriseObjectsClazz approach. Right at the top it says: In Java, static methods are similar to class methods in Objective-C, but one cannot use static methods in interfaces and static methods cannot be overridden by a subclass. Using the clazz pattern removes those limitations. However, I didn’t see any examples of this use, and spent a little time but couldn’t figure it out. Are there any examples out there? Thanks! Mark
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