yang686526

how to cancel oddbobject of being modified
how to cancel oddbobject of being modified
hi,
in objectarx there was a method acdbobject::cancel().
by using it i could cancell all the changes made by set...() methods at a writeenabled() object.
in my situation, i want to have layers protected by password.
i code the password as extended data to the layer and register a oddbobjectreactor to understand when the layer is being modified.
when a password-protected layer is about to be modified, how should i cancel the current changes in it?
(i suppose it is not good enough to throw an exception from the oddbobjectreactorenedformodify()?...)
thanks in advance for any help.
regards
chudomir
hi chudomir,
in dd we use transactions and undo mechanism (which is just another kind of transaction) to roll-back any changes in db. but as you probably understand transaction does not allow to roll back changes of a particular object -- it rolls back all changes in db from the moment it was started. so i suppose it's not suitable way for your task.
and what's the problem with exception in oddbobjectreactor:penedformodify() ? i would make so.
anyway, you can emulate cancel by storing object image at openedformodify() time and restoring it at modified() time via oddbobject::copyfrom().
exception seems better in case if you call some dd's function wich could modify protected layers then it will it prevents from braking data integrity in db.
hi dmitry,
currently i have 2 access points (functions) to the layers and have place the password protection on these points and not on the modification event of the layers - so it seems to satisfy my needs.
however it is still intersting to me the question of throwing an exception in the openedformodify() handler.
code:
{
// the reactor should throw the exception at the following point:
oddbobjectptr pobj = id.safeopenobject(oddb::kforwrite);
// do some set modifications here
}
if i throw some exception in the openedformodify() handler (it will be caught on upper level), will the internal state of the oddbobject data remain unchanged.
one of the principles of throwing exceptions is to leave the object in the same state after throwing an exception.
is the state of the oddbobject leaved unchanged in this case?
regards
chudomir
hi chudomir,
sure, the state of the oddbobject is leaved unchanged on exception thrown from the openedformodify() handler otherwise--it's a bug.-)
thanks - so it seems quite an easy way to protect somthing (even from myself )...
regards
chudomir