[xwiki-devs] [Proposal] Displayer Architecture for the future

Hi devs, I've been thinking about Displayer architecture today and here are my thoughts on how I see them implemented (without entering low-level details): Basics ====== * Everything in XWiki should be a Component and should be able to be implemented in Java and optionally extended in wiki pages (wiki components notion) * Have a Displayer component Role (ie a java interface for displayers) * Have default implementations in the display module for all basic types we want to support (textareas, date, string, number, etc). Basically this means rewriting the current displayers as components. * Allow to register Displayers defined in wiki pages by using wiki components (same mechanism as wiki macros). * Since a lot of Displayers are better written in wiki pages (javascript, css), create a UI submodule of the current display module which contains displayers we want bundled by default in XE (for ex for Dates and Users/Groups) * Extend the current {{display}} macro to support displaying Objects and Object Properties (it already supports passing an EntityType parameter but it's not used ATM). * The {{display}} macro will use the CM to get an instance of a displayer for the Object property type. It'll do by finding the XClass and getting the type from the XClass and then do a getInstance * Add an optional parameter to the {{display}} macro to support passing a displayer hint (by default it would use the "default" displayer for the property type). This will allow some pages to decide which displayer to use to render their content without being forced to use the default displayer. Advanced ========= In order to make it easy for a given class or a given object to decide how to display itself we could also define some special DisplayerBinding XObjects (one per property type). It could work like this: * If the {{display}} macro has the displayer hint specified as parameter then use it * If the {{display}} macro doesn't have the displayer hint specified then check if the xclass document has a DisplayerBinding XObject defined and if so use the displayer pointed to by the binding * If the {{display}} macro doesn't have the displayer hint specified and the xclass document doesn't have a DisplayerBinding XObject defined then check if the object to display have such an XObject and if so use it * Deprecate the notion of "custom displayer" that we have in our XClass since it wouldn't be needed anymore WDYT? I know we're not there yet but it would be cool to make progress on the direction we'd like to take. Thanks -Vincent