[Seaside] WAComponent children

[Julian Fitzell]

Hi Milan,

Components are supposed to be stateful and so are expected to live
longer than a single request. As such, you don't normally create them
without storing them somewhere or calling them. If you are doing this,
you might consider subclassing WAPainter instead.

The reason for #children is so the framework knows about all the
components it will render before rendering. It needs this in order to
save the components' state and to give them a chance to modify the
action URL for example. When you call a component, Seaside already
knows about it. If you create it, store it in an instance variable,
and then render it, you should return it in #children.

Technically you can create components lazily while rendering but as a
general rule I would avoid it. State snapshotting, updating the url,
and updating the document head all happen before rendering, so any
components created during rendering will not have these opportunities
until the next page view.

Julian

On 4/8/11, Milan Mimica <milan.mimica at gmail.com> wrote:
> Hello!
>
> If I understood correctly, each WAComponent instance is responsible of
> answering with an array of its child WAComponent instances. That is
> all I know and some things remain unclear to me.
> * Why exactly is this needed? It would help me understand how to use
> it properly.
>
> * Do I have to return the same children instances? Is the following legal:
> myComponent >> children
>     ^{child}.
> myComponent >> lazyInit
>     child := ChildComponent new.
> myComponent >> resetChildren
>     child := ChildComponent new.
>
> * Do child components, by consequence, need to be instance variables?
> Can I initiate child components on the fly like this:
> myComponent >> renderContentOn: html
> | child |
>     child := ChildComponent new.
>     html render: child.
>
>
> --
> Milan Mimica
> http://sparklet.sf.net
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