On Tue, Sep 03, 2002 at 09:57:31PM -0600, Luke Palmer wrote: > On Tue, 3 Sep 2002, Brent Dax wrote: > > > Damian Conway: > > # Neither. You need: > > # > > # $roundor7 = rx /<<roundascii>+[17]>/ > > # > > # That is: the union of the two character classes. > > > > How can you be sure that <roundascii> is implemented as a character > > class, as opposed to (say) an alternation? > > What's the difference? :) > > Neglecting internals, semantically what I<is> the difference?
I think the point still stands. How can you be sure that <roundascii> is implemented as a character class instead of being some other arbitrary rule? An answer is that perl should know how these things are implemented and if you try arithmetic on something that's not a character class, it should carp appropriately. Another answer might be that <<roundascii>+[17]> is actually syntactically illegal and you MUST perform character class arithmetic as <[abc]+[def]>. Somehow I prefer the former to the latter. -Scott -- Jonathan Scott Duff [EMAIL PROTECTED]
