Ever wondered if there was a way to stop Zope from barfing error messages all over your screen when one of your scripts crashes and burns? Well, guess what - there is! Meet the and tags, which can be used to trap and resolve errors in script execution.
Now, what you just saw was a very primitive exception handler, albeit one which isn't very useful on a production site. Ideally, you'd want the message generated by the exception handler to be a little more descriptive, and to contain some information on the source of the error.
DTML satisfies this requirement via two special, pre-defined variables - the "error_name" and "error_type" variables. Take a look:
<dtml-try>
<dtml-var CheckThisOut>
<dtml-except>
<b>Something's wrong
here! But what?</b><br>
This might help:<br>
Error type - <i><dtml-var
error_type></i>
<br>
Error value - <i><dtml-var error_value></i>
</dtml-try>
Here's the output:
Something's wrong here! But what?
This might help:Error type - KeyErrorError value - CheckThisOut
And if you flip back a couple of pages to the very first code snippet in this article, you'll notice a remarkable similarity between the default Zope error output, and that of the script above...not surprising, considering that Zope's default error screen also uses the same two variables.
/ 1 
