On Wed, May 30, 2012 at 2:03 AM, Robert Haas <robertmh...@gmail.com> wrote: > On Mon, May 28, 2012 at 4:38 PM, Magnus Hagander <mag...@hagander.net> wrote: >> On Mon, May 28, 2012 at 10:11 PM, Peter Eisentraut <pete...@gmx.net> wrote: >>> In 9.1, the pg_basebackup option --xlog takes no argument. In 9.2, it >>> takes a required argument. I think such compatibility breaks should be >>> avoided, especially in client-side programs. Now you can't write a >>> script running pg_basebackup that works with 9.1 and 9.2, if you need to >>> include the WAL. >>> >>> I think the behavior of -x/--xlog should be restored to the state of >>> 9.1, and a new option should be added to select between the fetch and >>> stream methods. (With a suitable default, this would also increase >>> usability a bit.) >> >> Just to be clear - it's not possible to actually accept -x with an >> *optional* parameter, is it? Meaning "-x" would mean the same as "-x >> fetch" and therefor become backwards compatible? >> >> IIRC I did try that, and didn't get it to work - but if that's doable, >> that seems like the cleanest way? > > Aren't you still going to have situations where it's the behavior > changes, if you go this route? > > Consider this command line: > > $ foo -b bar > > Is bar an argument to -b, or an argument to foo? If -b required or > forbade an argument it would be clear, but if the argument is optional > then it's fuzzy. Similarly, consider: > > $ foo -bar > > If -b takes no argument then this means the same thing as "foo -b -a > -r", but and if -b requires an argument then ar is the argument to > foo. If -b takes an optional argument, then it's ambiguous. > > I don't remember the exact behavior of getopt_long(), but I bet if we > go this route we'll find that there are cases where the behavior > changes vs. older releases; they'll just be subtler. Peter's > suggestion of a separate switch seems better to me for that reason.
You're right. I thought that optional parameter is possible because I recalled GNU extended getopt(3) supported that. After reading its man, I found that an argument must be in the same word as the option name to specify an argument, e.g., -xfetch (not -x fetch). This optional parameter looks confusing to a user. So I agree to add another parameter. Regards, -- Fujii Masao -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
