[Seaside] Seaside2: separation between content and presentation

[tblanchard@mac.com]

On Tuesday, December 3, 2002, at 12:13  AM, Avi Bryant wrote:

> Earlier versions of Seaside used a fairly similar model to WebObjects, 
> but
> had what I called the "polymorphic subcomponent problem": how do you
> change the class of a subcomponent at runtime, based on, for example, 
> the
> class of an entity object?  It was this problem that I was getting at.

Right - you use WOSwitchComponent.  WOSwitchComponent is a light 
wrapper that has a binding for classname and forwards all bindings to 
the wrapped component.

I just did an app that lets you build questionnaires on the web.  So we 
start out with the idea that a Questionnaire is an ordered list of 
elements.   Elements can be one of 4 things: Text, Divider, Question, 
or Questionnaire.  When you get to Question, we again have 4 types - 
FreeFormText, SingleChoice (Radio Buttons), MultipleChoice 
(Checkboxes), and FileUpload.

To render a questionnaire I have

GridLayout (essentially a table that can lay out horiz or vertically 
depending on a setting)
   Loop on elementList
     ElementView - which is a switch component - class name is derived 
from element.elementType

Depending on what type ElementView is - its just text, hr, the above 
(recursive inclusion - which is expanded again), or for a question a 
QuestionView.

QuestionView is itself a switchcomponent where the classname of the 
component is derived from element.question.questionType.  Its actually 
very clean.

>   In
> Seaside 0.94 you had to specify the class of the subcomponent in the
> bindings, just as you do below in WO.  This meant that setting up even 
> a
> simple tab control required tedious use of switch logic, and is IMO a
> serious flaw in the WO subcomponent system (but if there's a clean way
> around it I'd love to hear it).

WOSwitchComponent is pretty clean I think.  I can't think of any better 
way to do it in Seaside offhand.  How would you do it?