On 2/19/12 1:12 AM, Jonathan M Davis wrote:
On Sunday, February 19, 2012 00:43:58 Andrei Alexandrescu wrote:
On 2/18/12 8:00 PM, H. S. Teoh wrote:
From this and other posts I'd say we need to design the base exception
classes better, for example by defining an overridable property
isTransient that tells caller code whether retrying might help.
Just because an exception is transient doesn't mean it makes sense to
try again. For example, saveFileMenu() might read a filename from the
user, then save the data to a file. If the user types an invalid
filename, you will get an InvalidFilename exception. From an abstract
point of view, an invalid filename is not a transient problem: retrying
the invalid filename won't make the problem go away. But the application
in this case *wants* to repeat the operation by asking the user for a
*different* filename.
On the other hand, if the same exception happens in an app that's trying
to read a configuration file, then it *shouldn't* retry the operation.
I'm thinking an error is transient if retrying the operation with the
same exact data may succeed. That's a definition that's simple, useful,
and easy to operate with.
A core problem with the idea is that whether or not it makes sense to try
again depends on what the caller is doing. In general, I think that it's best
to give the caller as much useful information is possible so that _it_ can
decide the best way to handle the exception.
That sounds like "I violently agree".
Andrei
