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
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 and myApp.base 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.