Right. Sightly has the concept of a "Use" class (*). It is triggered from the template using a certain command/include. This use class can be either a) next to the script in the resource type folder (using the Java script engine if it's in Java, I think it could also be written in Javascript, in which case it uses the Javascript scrip engine) b) or it can be in a osgi bundle with the right package name (based on the rt) c) or it can be in a osgi bundle at any place (when addressed by fully qualified class name)
It has to extend a base class that will get the basic sling request information. But this can also be an extended base class that includes more: say in a CMS on top of Sling, there would be CMS specific base class that provides more context than the plain Sling stuff. The important part in this excercise is that it can be resource type based a) (specific logic just for the templates of that rt), but also easily shared among multiple resource types (c). Also, with super resource types things you want to be sure the correct use class is being used. So while I think it could be nice to have this happen more generically as part of the resource type execution, you need some place to specify that use class or request context helper. If we take it out of the template, where should it go? You could put it into the rt folder as e.g. jcr property - but what if different templates in the same rt want to use a different one? (Maybe that's something to avoid and we force it to be shared among all the templates within one rt). (*) like a bean, but wanted to avoid confusion of that name, so because the templates "uses" it, it's called that way) Cheers, Alex On 06.12.2013, at 08:48, Justin Edelson <[email protected]> wrote: > Hi Bertrand, > This looks a bit too magical to me :) All you're avoiding is a single > include line, right? Or am I missing something? > > You could also do the same thing (more or less) with a BindingsValuesProvider. > > Justin > > > > On Fri, Dec 6, 2013 at 11:40 AM, Bertrand Delacretaz > <[email protected]> wrote: >> Hi, >> >> From the funky prototypes department: I was talking to a colleague >> this week about how to minimize the amount of code in presentation >> templates, and we came up with the idea of having a setup script run >> at the beginning of the request processing, to prepare values, >> functions, iterators etc. for rendering scripts. >> >> I have created a prototype at >> https://svn.apache.org/repos/asf/sling/whiteboard/bdelacretaz/request-context >> - to play with it, install it, request >> http://localhost:8080/apps/requestcontext.html and see the commented >> scripts under /apps/requestcontext [2] >> >> Here's how this works: >> >> A Filter finds and executes the script that would process the same >> request as the current one if it had the "setup" extension, before the >> actual request processing takes place. >> >> In our example that's /apps/requestcontext/setup.ecma which contains things >> like >> >> rc.u.title = "Here's the title for " + rc.path + ", computed at " + >> new Date(); >> >> The rc object is our "request context", that provides easy access to >> standard (rc.<name>) and freely defined user values (rc.u.<name>). >> >> You can then use the rc object in the rendering script, which in this >> case would contain just >> >> <h1><%= rc.u.title %></h1> >> >> but the title building logic is neatly separated in its own script, >> reusable, doesn't pollute rendering etc. >> >> This might be especially useful in the context of templating languages >> like Sightly [1] that want to avoid code in rendering templates. >> >> The setup script can also play the role of a mini-controller, as it >> can redirect, fail or forward the current request. >> >> My prototype doesn't require any changes to the Sling code, so we can >> very keep that as an experimental extension for now, if we want to >> move it out of the whiteboard. >> >> Feedback is welcome as usual. >> >> -Bertrand >> >> [1] >> http://www.pro-vision.de/content/medialib/pro-vision/production/adaptto/2013/adaptto2013-sightly-gabriel-walt-honwai-wong-senol-tas-pdf/_jcr_content/renditions/rendition.file/adaptto2013-sightly-gabriel-walt-honwai-wong-senol-tas.pdf >> >> [2] >> https://svn.apache.org/repos/asf/sling/whiteboard/bdelacretaz/request-context/src/main/resources/SLING-CONTENT/apps/requestcontext
