On Fri, Nov 02, 2012 at 03:40:20PM -0500, Adam Heath wrote: > On 11/02/2012 12:49 PM, Ben Pfaff wrote: > > On Mon, Oct 29, 2012 at 03:03:13PM -0500, Adam Heath wrote: > >> On 10/29/2012 11:34 AM, Ben Pfaff wrote: > >>> Until now, a command like "ovs-vsctl --may-exist add-br br0" yielded a > >>> confusing error message. Users had to realize that the correct form was > >>> "ovs-vsctl -- --may-exist add-br br0", but instead they often reported a > >>> bug or gave up in frustration. Even though the behavior was documented, > >>> it > >>> was counterintuitive. > >>> > >>> This commit allows command-specific options to be mixed with global > >>> options, making both forms of the command listed above equally acceptable. > >> > >> Tbh, I would actually prefer to have command-specific options that > >> appear in the global area issue an error. > >> > >> == > >> one-vsctl: Found command-specific --may-exist in global area, please > >> use -- instead. > >> == > >> > >> See (1) for a reason why I'd prefer it the way I suggested above. > >> > >> 1: http://lwn.net/Articles/520198/ > >> you might need to wait a few days for it to become publically > >> available. > > > > OK, it's available now, and I skimmed over it, but the analogy to > > ovs-vsctl isn't really obvious to me. Can you elaborate? > > Providing variants for valid parameter processing makes it harder to > understand. Instead, a warning/error should be issued saying the arg > is not understood(and if it appears to be a per-cmd option in global > space, then a message saying such should be displayed), but allowing > for per-option to work for global is actually *breaking* existing > scripts that error out. > > Any existing script that places --may-exist in global space, without > --, will currently have an error. Your patch changes that. So, that > is bad. Instead, if you just change the error message displayed in > those cases, then there isn't any breakage.
I still don't understand. Why would an existing script call ovs-vsctl with --may-exist as a global option? The call would not do anything useful, because it would exit with a fatal error every time. Taking this argument to its logical conclusion, one must never extend any program by adding a new option, because it could break some existing script that tries to use that (nonexistent) option. _______________________________________________ dev mailing list dev@openvswitch.org http://openvswitch.org/mailman/listinfo/dev
