Re: How to call TPyException in Python?

Hello Wim,

> but I guess
> what you want is a downcast of the exception to the actual type, check
> whether there's a dictionary available and then turn it into that type on
> the python side?

Yes. If I can know the type of the exception, my code will be, for example, as follows.

try:

    ROOT.GetDataFromMyDetector()
except ROOT.MyExceptionWriteError, e:

    print "Cannot write data on the disk"     # cont...
except ROOT.MyExceptionNoResponse, e:

    print "No response from the detector"     # cont...
except:

    print "Unknown error"
    # cont...

But in the case of Exception, it will be if-elif instead. I prefer the above script.

try:

    ROOT.GetDataFromMyDetector()
except Exception, e:

    if e.message == "Cannot write data on the disk":

        print e
        # cont...
    elif e.message == "No response from the detector"
        print e
        # cont...
    elif:
        print "Unknown error"
        # cont...

> Not impossible, just scary to put a lot of work inside a catch block of
> an exception handler. :} (If something else goes wrong and there is a
> second exception, the application would terminate.)

Are you talking about end-user-side work or dev-team-side work?

Regards,

--
OKUMURA, Akira oxon@{astro.isas.jaxa.jp,stanford.edu}
Institute of Space and Astronautical Science (ISAS/JAXA)
Now at KIPAC/SLAC/Stanford
Varian Physics #306, 382 Via Pueblo Mall, MC 4060
Stanford, CA 94305-4060
TEL 650-736-0971/FAX 650-724-5065
Skype : okumura.akira

On 2011/05/04, at 11:19, wlavrijsen_at_lbl.gov wrote:



> Akira,

> 

>> According to your explanation, it seems that my own exception classes
>> derived from std::exception are not useful because they are all turned
>> into single class, Exception. Therefore, if I want to distinguish different
>> type of errors (exceptions) from each other, I always have to check
>> Exception.message in if statement instead of try statement. Am I correct?


> 

> that is the case. I can fix that for the known exceptions that map nicely

> onto python ones, and I can probably even add the type name, but I guess

> what you want is a downcast of the exception to the actual type, check

> whether there's a dictionary available and then turn it into that type on

> the python side?

> 

> Not impossible, just scary to put a lot of work inside a catch block of

> an exception handler. :} (If something else goes wrong and there is a

> second exception, the application would terminate.)

> 

> Best regards,

>           Wim

> -- 

> WLavrijsen_at_lbl.gov    --    +1 (510) 486 6411    --    www.lavrijsen.net