🚀 go-pugleaf

Matt> If an object can throw 18 exception types, then clients will need
Matt> to understand all those types, and their implications -- and
Matt> perhaps then, something of the internal workings of that object,
Matt> in order to understand how to respond to a particular exception.

By carefully deriving exception types, the clients needn't worry about
details they really don't understand or care about.

Matt> It might be better to cause the functions in the objects
Matt> interface (the top level functions of the object) to throw only a
Matt> limited set of exceptions, perhaps only one, and handle all other
Matt> exceptions themselves (print an error message or log, take some
Matt> constructive action, etc.).

Rather, let them throw any number of exceptions, but make sure the
exception types have a limited number of distinct base classes. The
ability to derive exception types is the very feature that makes C++
exceptions superior to -- say, Ada's. Client code can catch them with
the accuracy it needs to instead of what the library says.


==pena
--
Olli-Matti Penttinen <pena@niksula.cs.hut.fi>
Lehdesniityntie 3 F 91
00340 HELSINKI                     "When in doubt, use brute force."
tel. + 358 0 1399 0110                -- Ken Thompson