pramsey at refractions.net
Tue Apr 22 16:43:51 EDT 2003
Martin Davis wrote:
> Yes, absolutely. The whole idea behind structured exception handling
> is so that higher layers of client code can catch some or all of them
> and handle them intelligently. To do this, exceptions need to be
> typed, and they often need to carry extra information about the
> nature of the error.
> If every exception thrown is a string, the only handling strategy
> possible is to abort printing out the string.
> It's easy to degrade exceptions to strings, but very hard to make
> them back into typed exceptions. If typed exceptions are causing a
> problem, the answer is to catch them all in the "C PostgresQL
> wrapper" and convert them to strings.
Unfortunately that is not an option for us, because the act of throwing
the exception also sends the backend a sigabort. The backend is dead
before it can catch the exception.
Don't worry about making any changes until Dave gets back and can
provide more detailed guidance. I don't know that there is any guarantee
that string-based exceptions would be any more catchable and any less
deadly to us.
> Martin Davis, Senior Technical Architect Vivid Solutions Inc. Suite
> #1A-2328 Government Street Victoria, B.C. V8T 5G5 Phone: (250)
> 385 6040 Fax: (250) 385 6046 EMail: mbdavis at vividsolutions.com
> Web: www.vividsolutions.com
>> -----Original Message----- From: Paul Ramsey
>> [mailto:pramsey at refractions.net] Sent: Saturday, April 19, 2003
>> 12:23 AM To: GEOS List Subject: [geos-devel] Exceptions
>> The exceptions continue to muck with us. Exceptions thrown in geos
>> have not been catchable, and are taking down the postgres backend
>> with sigabort. I did a grep for "throw" in the source code, and the
>> exceptions are a bit of a mishmash. Most of them are of the form,
>> throw "PointCoordinateList exception: can't retrieve element\n";
>> But some are of the form,
>> throw new ParseException(e.toString());
>> throw ParseException("Expected number but encountered ')'")
>> So, sometimes we are throwing strings, sometimes we are throwing
>> new exception objects and other times just static things?
>> Anyhow, we have had better luck catching the simple throws (the
>> strings). Is there a reason for throwing specially constructed
>> exception objects?
>> Paul Ramsey Refractions Research Email: pramsey at refractions.net
>> Phone: (250) 885-0632
>> _______________________________________________ geos-devel mailing
>> list geos-devel at geos.refractions.net
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| Paul Ramsey
| Refractions Research
| Email: pramsey at refractions.net
| Phone: (250) 885-0632
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