[Tapestry Wiki] Update of "Tapestry5HowToNotMakeCustomComponent" by DavorHrg

[Apache Wiki <wi...@apache.org>]

Dear Wiki user,

You have subscribed to a wiki page or wiki category on "Tapestry Wiki" for change notification.

The following page has been changed by DavorHrg:
http://wiki.apache.org/tapestry/Tapestry5HowToNotMakeCustomComponent

New page:
I wanted to create a custom component and ended up doing few things the wrong way. Some will find these thing obvious, but I belive to some it will be usefull as well.

== beforeRenderTemplate / beforeRenderBody ==
Documentation clearly states that if a component doesn't have body, !RenderBody phase is skipped, never the less I used that phase to create a custom component that outputs HTML by it self. What happened is that it worked when I used the component this way:
{{{
<t:MyComp source="listData"> </t:MyComp>
}}}
but it did not work when the space between tags was removed, or written as single tag
{{{
<t:MyComp source="listData"/>
}}}
If you don't intend to use the template supplied to your component's body (between tags), the proper place for your code is inside beforeRenderTemplate.

''HINT: you can use @!BeforeRenderTemplate, @!BeforeRenderBody annotations instead method names''

== non component classes/interfaces in myApp.pages and myApp.components packages ==
pages and components are instrumented by tapestry, they are also in a separate class loader, and you should avoid using their packages for any non component classes/interfaces. You are most likely to get '''!ClassCastException''' or '''!CoercionException'''.

For me these problems were result of trying to make a component as fast as I can.
I was eager to use the class reloading feature, and was also lazy to separate an interface to a top level class, so I created an interface for a !ListModel in my component and implemented it as inner class of the test page.
I was perplexed by the exceptions that were thrown, and at first thought that the cause was in me using generics.
At this time I can not in detail explain why these errors occur, but to recommend avoiding this situation.

---------------------------------------------------------------------
To unsubscribe, e-mail: dev-unsubscribe@tapestry.apache.org
For additional commands, e-mail: dev-help@tapestry.apache.org