On Tue, 2004-01-13 at 17:22, Bill Horsman wrote: > (Yet) another solution: > > Get the JexlContext to track which variables it was asked for. Note > which ones were known and which were not known. Then you can ask > JexlContext for the list at the end.
I got so enthused by this idea that I decided to just do it. There is a
new method on Expression:
CheckResults check(JexlContext context) throws Exception;
And CheckResults contains:
Object getAnswer();
String[] getKnownVariables();
String[] getUnknownVariables();
String[] getUsedVariables();
(It's documented better in the patch).
Good things:
It doesn't break the current API
It gives more information than before: a list of all the unknown
variables (not just the first one encountered), and a list of all the
used variables (this is a nice to have for my current app)
Bad things:
It needs to clone the JexlContext to make it thread-safe. This is done
transparently, but it might effect performance. But then again, I don't
think it's significant. (Actually, as I write this I realise that it
doesn't need to clone it - just wrap it. But the shallow clone of Map is
not too lengthy anyway).
It's not a simple configuration change to make it lenient or strict. You
need to call a different method (check instead of evaluate). I suppose
you could make evaluate do something similar (and just throw an
exception that contained the CheckResults or something).
The patch is an tar archive because I still haven't found a way of
bundling the new files in the patch file. The archive contains two new
Java files and the patch file.
- Bill
jexl-bh-3.tar.gz
Description: application/compressed-tar
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