On Mon, Nov 21, 2005 at 09:02:57AM -0800, Larry Wall wrote:
> : There's also <sp>, unless someone redefines the <sp> subrule.
>
> But you can't use <sp> in a character class. Well, that is, unless
> you write it:
>
> <+[ a..z ]+<sp>>
>
> or some such. Maybe that's good enough.
Er, that's now <+[ a..z ]+sp>, unless you're now changing it back.
> : And in the general case that's a slightly more expensive mechanism
> : to get a space (it involves at least a subrule lookup). Perhaps
> : we could also create a visible meta sequence for it, in the same
> : way that we have visible metas for \e, \f, \r, \t. But I have
> : no idea what letter we might use there.
>
> Something to be said for \_ in that regard.
Yes, I thought of \_ but mentally I still have trouble
classifying "_" along with the alphabetics -- '_' looks more
like punctuation to me. And in general we use backslashes
in front of metacharacters to remove their meta meaning
(or when we aren't sure if a character has a meta meaning),
so that \_ somehow seems like it ought to be a literal
underscore, guarding against the possibility that the unescaped
underscore has a meta meaning. (And yes, I can shoot
holes in this line of thinking along with everyone else.)
Whatever shortcuts we introduce, I'll be happy if we can just
rule that backslash+space (i.e., "\ ") is a literal space
character -- i.e., keeping the principle that placing a backslash
in front of a metacharacter removes that character's "meta"
behavior.
> I dunno. If «...» in ordinary code does shell quoting, maybe «...» in
> rules does filename globbing or some such. I can see some issues with
> anchoring semantics. Makes more sense on a string as a whole, but maybe
> can anchor on element boundaries if used on a list of filenames.
> I suppose one could even go as far as
>
> rule jpeg :i « *.jp{e,}g »
>
> or whatever the right glob syntax is.
Since we already have :perl5, I'd think that we'd want globbing
to be something like
rule jpeg :i :glob /*.jp{e,}g/
or, for something intra-rule-ish:
m :w / mv (:glob *.c)+ <dir> /
And perhaps we'd want a general form for specifying other
pattern syntaxes; i.e., :perl5 and :glob are shortcuts for
:syntax('perl5') and :syntax('glob') or something like that.
Pm
