Exception Handling In DTML - ...And One For All (
Page 6 of 10 )
Now, the <dtml-try> statement can only deal with exceptions that it knows about. What about the ones the developer can't predict?
DTML also allows you to specify a catch-all exception handler, one which handles *any* type of exception generated - simply omit the exception name from the <dtml-except> statement. The following code snippet illustrates this technique:
<dtml-try>
<dtml-var alpha> divided by <dtml-var beta> is <dtml-var
expr="_.int(alpha)/_.int(beta)"
>.<br>
<dtml-except>
<b>Something bad happened. Call 911.</b>
</dtml-try>
You can even combine this with exception handlers for specific exceptions.
<dtml-try>
<dtml-var alpha> divided by <dtml-var beta> is <dtml-var
expr="_.int(alpha)/_.int(beta)"
>.<br>
<dtml-except KeyError>
<b>Missing variable.</b>
<dtml-except
ValueError>
<b>Illegal value.</b>
<dtml-except>
<b>Something bad
happened. Call 911.</b>
</dtml-try>
This way, when an exception occurs, Zope will first check to see if an exception handler has been defined for that exception type. If so, the appropriate handler is invoked; if not, the exception is routed to the catch-all handler, which displays a generic error message.
/ 1 
