Mike,Have you done any performance testing on this? I would have question about invoking OGNL for each binding. I am not saying this is bad just that the core WO is made to be very efficient and that pose some constrains on what we can do. I know that RoR has some very nice feature but it is also very slow. We have to find a happy medium, the Association factories are quite efficient and the overhead is very minimal but there is a bit more code to write, although we could probably template a lot of it.
As for the comments in bindings I agree. I have not had time to look into it, would you like to?
Pierre -- Pierre Frisch [email protected] On Jun 30, 2009, at 10:13, Mike Schrag wrote:
This requires an association factory registered per function, though, right? Part of the niceness of helpers is how they are registered and resolved ...For instance, I can just create PersonHelper, and somePerson| displayName will automatically look for PersonHelper and call displayName on it, just based on the type of the bound object. It will also walk the inheritance tree, so you can have EOGenericRecordHelper and it will look up the inheritance tree to find the class or interface helper that defines the function you're referencing (so you can do "$anyEO|id" and it will call EOGenericRecordHelper.id(eo) ). Also, because it's implemented behind the scenes as an OGNL expression, you can pass arbitrary params "for free" -- so I can do "$paragraph|highlight(word)" and it will call StringHelper.highlight(String paragraph, String word). On top of that, if your binding evaluates to null (say "somePerson" was a null in the first example) it actually computes the Class name of the bindings (we have an NSKVC impl that operates purely on Classes, not on the objects themselves) and figures out what type the object WOULD have been (obviously limited by what you declare it to be) and calls the appropriate helper passing a null, so you can do helpers with null values. So in the first example somePerson was null, it would figure out that somePerson was a Person class from the type declaration of the binding (this works on keypaths too) and would dispatch to PersonHelper.displayName(null) so you can display "No name available" (or whatever).My impression, though, is that it's quite a bit more programmatically expensive to register functions in the 5.4 parser and it wouldn't have the fancy scoping or resolution. I think maybe you'd have to do something like "helper: person|displayName", maybe, and parse it with a fancier association factory?In the Wonder one, the way we do it is that as it parses, it actually turns into an OGNLAssociation behind the scenes, and we just jam the parameters onto the end of the registry lookup. For example, that "$paragraph|highlight(word)" becomes:~ @ognl .helperfunction .WOHelperFunctionRegistry @registry()._helperInstanceForFrameworkNamed(#this, "paragraph", "highlight", "app").highlight(paragraph, word)it's sort of magical, but actually works :) gotta love ognl ...Oh, the other thing that would be nice in the 5.4 parser is support for "// VALID" There are cases where the WOLips validator can't provably validate an expression (not often, but happens). The Wonder parser has an extension to WOD and inline bindings that allows you to do:Test : WOString { value = someKVCExpressionThatCantBeStaticallyResolved; // VALID } and<wo:str value="$someKVCExpressionThatCantBeStaticallyResolved // VALID"/>so the WOLips validator can hide warnings on them. ms On Jun 30, 2009, at 12:36 PM, Mr. Pierre Frisch wrote:Mike there is only one space difference: <wo:string value="[person|displayName]" /> or <wo:string value="[displayName: person]" /> Cheers Pierre -- Pierre Frisch [email protected] On Jun 29, 2009, at 15:46, Mike Schrag wrote:I suppose we just need to integrate them as association and add them to the association factory. This is trivial to do.yeah, i'm pretty sure 5.4's parser can do it with a custom factory, but I'm concerned about how much typing it will require to actually use it ... helpers are cool because it's so easy to drop into a binding (change from "$person" to "$person| displayName"). if you have to switch to a different association namespace to get it on a binding, i think it might suck more, but I'll withhold judgment.ms _______________________________________________ Do not post admin requests to the list. They will be ignored. Webobjects-dev mailing list ([email protected]) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/webobjects-dev/pierre%40apple.com This email sent to [email protected]
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