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Postings from August 2010
On Thu, Aug 19, 2010 at 04:58:48PM +0200, Abigail wrote: > On Thu, Aug 19, 2010 at 03:42:27PM +0100, Zefram wrote: > > Abigail wrote: > > > '(?si-xm:)' tells me exactly what's > > >enabled, and what's disabled, regardless of the Perl version. > > > > No, it doesn't. It doesn't tell you whether the /p flag is enabled. > > It does. It tells me that pattern following the : neither enables, nor > disables /p. Whether /p is in effect is inherited from the enclosing > pattern. > > I can take '(?si-xm:PATTERN)', and know what it does by itself. Regardless > of Perl version. If someone comes to me and ask what '(?si-xm:PATTERN)' > means, I can explain it to him. If he comes with '(?~-xm:PATTERN)', I'll > have to reply "well, that depends on the version of Perl you're running". [I'll use (?~, but the current patch proposes (?^] (?~-xm:) means "defaults, and then turn off x and m. So it's a tautology. Therefore I'd argue that use of a - in a (?~ should be a syntax error. No options can default to on. If they are on by default, then by the same reasoning, you can't tell me what qr/PATTERN/ is going to do, without asking me the perl version. With the axiom than "all options default to off, and always will" then I believe there is no regexp that can be written with the new syntax that is ambiguous. Nicholas ClarkThread Previous | Thread Next