On Jun20, 2011, at 03:16 , Greg Stark wrote: > On Fri, Jun 17, 2011 at 3:49 PM, Florian Pflug <f...@phlo.org> wrote: >>> The regex is always to the right of the operator. >> >> Which is something you have to remember... It's not in any >> way deducible from "foo ~ bar" alone. > > Except that it's always been this way, going back to perl4 or tcl or > their predecessors. The regexp binding operator always has the regexp > on the right.
Yeah. The strength of that argument really depends on one's prior exposure to these languages, though... >>>> How is that worse than the situation with "=~" and "~="? >>> >>> With =~ it is to the right, with ~= it is to the left. >> >> It's always where the tilde is. Yeah, you have to remember that. > > And when you get it wrong it will fail silently. No errors, just wrong > results. Yeah, but this is hardly the only case where you'll get unintended results if you mix up operator names. Now, one might argue, I guess, that mixing up "=~" and "~=" or more likely than mixing up, say, "~" and "~~". But ultimately, whether or not that is highly dependent on one's personal background, so we're unlikely to ever reach agreement on that... > While I've never accidentally written /foo/ =~ $_ in perl I have > *frequently* forgotten whether the operator is ~= or =~. Actually I > forget that pretty much every time I start writing some perl. I just > put whichever comes first and if I get an error I reverse it. Yeah, the nice thing in perl (and ruby also, which is *my* background) is that regexp's and strings are distinguished by the type system, and also by the parser. The latter (i.e. regexp literals enclosed by /../) probably isn't desirably for postgres, but the former definitely is (i.e. distinguishing regexp's and text in the type system). Please see the thread "Adding a distinct pattern type to resolve the ~ commutator stalemate" for the details of the proposal. > I can see the temptation to make it symmetric but it's going to cause > an awful lot of confusion. I do believe that by adding a distinct type we can actually *reduce* confusion. It makes "text ~ pattern" readable even for people who don't intuitively know that the pattern always goes on the right. best regards, Florian Pflug -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
