Java Boutique has an interesting article about exceptions that you might find useful.
What I like about exceptions is fairly straightforward. If I have a GUI (A) which issues a message to some object (B) which in turn sends a message requesting data from object (C), what happens if C determines that the data is bad due to user input (and not, say, a programming error)? There's probably no point in issuing a warning in the error log (because it's not an error from a programming standpoint) and there's no point in killing the application because a user typed something stupid (an all too common event, though).
In the above scenario, C throws in exception and B catches it. B then checks the exception to see if anything unusual needs to be done. If the exception is caused by failing to select a required option, no big deal. If the exception is caused by a bad password, perhaps it is a big deal. B can decide whether or not to log the exception and do further processing. B, at this point, rethrows the exception and A catches it. Because A is simply the GUI, A doesn't worry about logging the exception. A simply has to have some method of displaying the exception to the end user in a meaningful way.
Thus, with an exception based system, particularly if it's multi-tiered, you have full control of the error processing rather than simple die and warns. Further, uncaught exceptions will kill the program when encountered during execution, thus making them morely likely to be reported in testing and feedback -- which in turns means they are more likely to be handled appropriately and leads to more robust code.
New address of my CGI Course.
Silence is Evil (feel free to copy and distribute widely - note copyright text)
Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
Read Where should I post X? if you're not absolutely sure you're posting in the right place.
Please read these before you post! —
Posts may use any of the Perl Monks Approved HTML tags:
You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
- a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
Link using PerlMonks shortcuts! What shortcuts can I use for linking?
See Writeup Formatting Tips and other pages linked from there for more info.
| & || & |
| < || < |
| > || > |
| [ || [ |
| ] || ] ||