On Thu, November 1, 2012 00:24, Giuliano Colla wrote: > Il 31/10/2012 14:45, Jonas Maebe ha scritto: >> On 31 Oct 2012, at 14:35, Giuliano Colla wrote: . . >>> but if it doesn't it's a Delphi bug, I'd say. What are exceptions >>> there for, if not for telling you that what you requested cannot be >>> done? >> >> There are multiple ways to indicate a failure. Exceptions are a very >> expensive way for doing so, and generally should only be used in cases >> that are truly exceptional and/or indicate a fatal error. In other >> cases, using a special return value is generally much more appropriate. >> >> > My bad. I hadn't realized that low level file operation such as FileOpen > and FileCreate do not raise an exception on failure. I seldom use them, > and only in connection with physical devices, where I always take care > to verify the existence before attempting to read or write. So I just > relied on a useless try-except construct. > It's very unlikely that such a failure would permit a program to > continue running, I'd call it a fatal error, so an exception would be > welcome, but that's life...
I don't agree with your statement that such an error wouldn't allow the program to continue running. Vice versa, there are many situations where the result may be used for a different behaviour of the respective program. As an example, you may use the return value from FileCreate for checking whether the user supplied a valid file name in his input to the program (and ask for another file name afterwards), you may also check whether you can access the respective file in read/write mode (and thus allow user to change the file) or you need to stick to read-only mode (and thus allow just viewing/reading the content), etc. Tomas _______________________________________________ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-pascal
