Aren t There Exceptions?

Aren't There Exceptions?

As our technological powers grow, the portability and flexibility of our computer hardware grows, too. Modern computers can be connected to and disconnected from networks and peripherals without having to first power down. This means that it is now normal for hardware to appear and disappear ad hoc. Printers, modems, and file servers can come and go like the tides. With the development of wireless networks such as WiFi and Bluetooth, our computers can connect and disconnect from networks frequently, easily, and soon, transparently. Is it an error if you print a document, only to find that no printers are connected? Is it an error if the file you are editing normally resides on a drive that is no longer reachable? Is it an error if your communications modem is no longer plugged into the computer?

The deeper we wade into the Internet ocean, the more this conundrum of here-today-gone-tomorrow becomes commonplace. The Internet can easily be thought of as an infinite hard disk—one that is out of the control of any one person, company, or system administrator. A valid pointer today can be meaningless tomorrow. Is this an error?

None of these occurrences should be considered as errors. If you try to print something and there is no printer available, your program should just spool the print image to disk. The print manager program should quietly indicate when it reconnects to a printer while it has unprinted documents in its queue. This should be an aspect of normal, everyday computing. It is not an error. The same is true for files. If you open a file on the server and begin editing it, then wander out to a restaurant for lunch, taking your notebook with you, the program should see that the normal home of the file is no longer available and do something intelligent. It could use the built-in WiFi card to log onto the server remotely, or it could just save any changes you make locally, synchronizing with the version on the server when you return to the office from lunch. In any case, it is normal behavior, not an error.

Almost all error message boxes can be eliminated. If you examine the situation from the point of view that the error message box must be eliminated and that everything else is subject to change in search of this objective, you will see the truth of this assertion. You will also be surprised by how little else needs to be changed in order to achieve it. In those rare cases where the rest of the program must be altered too much, that is the time to compromise with the real world and go ahead and use an error message box. But the community of programmers needs to start thinking of this compromise as an admission of failure on the its part: that it has resorted to a low blow, a cheap shot, like a GOTO statement in its code.

Still, we would like to see an error message on our screen if the printer catches on fire. Error messages should be reserved for just such real emergencies.