Component to format null values

[Dmitriy Vsekhvalnov]

Hello all,

i'm looking to some approach to render property value or some default string
if value is null.

Something like:
   <t:formatnull value="contract.name" />

I have no problem to implement such component,but i want this to work with
property chains as well:

  <t:formatnull value="contract.manager.address.city.name" />

where i want default string to be rendered, if any of intermediate values
evaluated to null. Now i'm getting NPE.

Is there are any service in tapestry which i can use for property
expressions evaluation or any other ideas?

Thanks.