[Seaside] #call: #answer / sessions
ramon.leon at allresnet.com
Thu Jan 18 20:51:51 UTC 2007
> I have a couple of basic questions
> Is it OK to #call components that never #answer ? For
> instance if you have a page with a menu that #calls
> components for each of its menu items, and the user may do
> this again before the component #answer.
> I believe this is the case, for instance, on the Sushi Store,
> where a user can be adding sushi to the cart and click on the
> Browse link on the menu bar, which will #call the browsing
> component again, before answering.
> The question is: Will this generate a memory leak ? Will all
> those compoenents add up ? Or is this the proper way to do it?
Yes, it's ok. It might help if you think of #call: as simply display this
component instead of this other component. A component doesn't have to
answer, nor are you always interested in its answer.
self call: Component new
Replaces self with a new component, whereas if you simply wanted to render a
component without replacing it in the UI, you'd
html render: self someComponent
In the render method of the outer component.
> I'm asking because I am developing my first real basic, but
> comertial application in Seaside, and I have not cached up
> with it real well yet.
> I have a very simple page, with a header, a navigation bar
> and a main area, very similar to the Sushi Store. But I have
> a WAComponent for each of those (header, navbar, etc.),
> placed an the page using divs.
> The component of the navication bar, simply shows some
> options that when clicked, #call the proper component to be
> displayed on the main area. What I have to do for the
> component to be displayed on the main area is calling the
> #call method from the previous component that is on the main
> area, otherwise this newly selected component will be
> displayed on the navigation bar DIV.
> Is this the proper way to build a basic web app that displays
> a specific component for whatever is clicked on the navigation bar?
Yes, this is correct. I like to have a currentComponent in a layout like
this, and simply have the menus say
currentComponent call: SomeNewComponent new.
>From the outer container, which acts like a mediator controlling what item
is displayed. Expect the component to get garbage collected after it's no
longer displayed since you're not holding onto a reference. If you want to
reuse existing components rather than creating them on each invocation, you
currentComponent call: (self componentFor: SomeNewComponent)
^components at: aComponent ifAbsentPut:[aComponent new]
And use the components class as a key into a dictionary so you can reuse the
same instance each time they click that menu item. Since you're holding a
reference to it, it won't be gc'd just because it's not displayed and you
can use the original instance over and over, meaning it'll maintain any
state it previously held, a sometimes very useful and unexpected thing in a
> When you develop a login process, like the one in Ramon's
> blog. Where is it proper to store the user that is logged
> on? Is this supposed to be stored somewhere in the WASession?
Yes, a custom session class is a good place for this, so you can have access
to it from every component with a simple..
self session currentUser
Also common is
self session database
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