Re: Exceptions and Errors

Hello Adam, Wednesday, April 14, 2004, 7:36:43 AM, you wrote: > On Wed, 14 Apr 2004, Marcus Boerger wrote: > Hello Marcus -- >> > This is actually a pretty nasty side effect of throwing exceptions in >> > ctors because these two lines have *very* different results if they >> > fail: >> >> > $db = new SQLiteDatabase(); >> > $db = sqlite_open(); >> >> sqlite_open returns a resource and new SQLiteDatabase returns an object. >> The latter is a ctor and to prevent it throwing exceptions you'd need to >> provide a factory method, make the ctor private (which prevents inhering) >> and then look ofr all possible kinds of failures before calling the ctor. > I understand the differences between the two. However, I believe that > most people view these two actions as identical. In their minds, the > only difference is whether they're using a procedural or OO API to > create a connection. > I realize, for current technical reasons, ctors need to throw > exceptions; however, the end result is that changing from one API to > another ends up turning a failed database connection from a harmless > warning to a fatal error. > This seems bad because it's not an obvious side effect. Additionally, > given the current anti-exception sentiment on this list, it also seems > odd to essentially require all object instantiations (but only > instantiations) to be wrapped inside a try/catch block, or risk an > immediate script termination. > Is there anything we can do to preserve the ability to alert > developers to errors during the construction process without also > forcing them to catch exceptions? The way to avoid exceptions in ctors is using empty exceptions and issuing E_WARNINGs or E_ERRORs from every method when the instance wansn't initialized already. If you think twise this is worse and also comes along with a speed penalty from the additional checks. Anyway if you don't want to deal with exceptions in ctors then you probably might not want to deal with oo at all. marcus