On Sat, Jul 11, 2009 at 2:11 PM, rb <[email protected]> wrote: > > Isn't it true that the choice between using a return error code and > using the exception mechanism is decided by whether the result is > expected or not?
Well, "exceptional condition" means out of the ordinary - you have no doubt used try/except on file opens, db connections, etc. The motivations I have seen most often for what you quote above is the "weightiness" of exception mechanisms, that is to say return codes are preferred when exceptions mean a performance hit. But exceptions have the distinct benefit of de-coupling. If _I_ raise an exception, what I say is "someone violated my contract: I have preconditions I expect to operate in" --- raising an exception doesn't care who caused it, or who should handle it - handling is left to the responsibilty of the callee... SO that is the benefit of exceptions. Wondering what the exception structure overhead is in Python (because of your post), I looked a little, and found this: http://blog.hackers-cafe.net/2009/02/python-to-raise-exception-doesnt-take.html So it seems exception overhead in Python is non-existent.... which leaves the choice to merely the best choice structurally (performance doesn't need to be a consideration). Regards, - Yarko > If record_not_found is a common, reasonably expected > outcome then maybe it is better to use a return code to signal this so > that the logic to deal with it is inline with the algorithm of the > function. If a record exists but the read fails that might always be > an exception case, but trying to read a record and not knowing first > whether it exists may be better handled by the inline control logic. > > That is, don't most other systems use a return code to single > not_in_table rather than using exception facility? > > Isn't it best to reserve use of the exception mechanism for errors > that should _rarely_ happen and needn't be covered by the inline > logic? > > -- > > On Jul 11, 9:06 am, Vidul <[email protected]> wrote: > > Probably RecordNotFound exception or just an attribute like > > crud.setting.record_not_found? > > > > On Jul 11, 7:01 pm, mdipierro <[email protected]> wrote: > > > > > You are right. we need to deal with that exception somehow. What do > > > you propose? > > > > > massimo > > > > > On Jul 11, 10:13 am, Vidul <[email protected]> wrote: > > > > > > For example: > > > > > > def update_comment(): > > > > form=crud.update(db.comment, request.args(0)) > > > > retur dict(form=form) > > > > > > where args(0) does not exist in the database. > > > > > > On Jul 11, 5:51 pm, mdipierro <[email protected]> wrote: > > > > > > > What kind of exceptions? > > > > > > > On Jul 11, 7:04 am, Vidul <[email protected]> wrote: > > > > > > > > Hi, > > > > > > > > Auth and CRUD are amazing, no doubt, but is there a best practice > for > > > > > > the exception handler / ing of read / create / update / delete > > > > > > actions? > > > > > > > > Thank you! > > > --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "web2py Web Framework" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/web2py?hl=en -~----------~----~----~----~------~----~------~--~---
