Re: ?{ } block in regexes?

2005-07-11 Thread Yuval Kogman 
On Mon, Jul 11, 2005 at 00:03:08 -0400, Rick Delaney wrote:

 The trivial way:
 
 my $thing = qr/
 (?{ $obj = create() }

did you mean ?{ local $obj = create() }?

-- 
 ()  Yuval Kogman [EMAIL PROTECTED] 0xEBD27418  perl hacker 
 /\  kung foo master: /me wields bonsai kittens: neeyah



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Re: ?{ } block in regexes?

2005-07-11 Thread Rick Delaney 
On Mon, Jul 11, 2005 at 05:00:45PM +0300, Yuval Kogman wrote:
 did you mean ?{ local $obj = create() }?

Yes.

-- 
Rick Delaney
[EMAIL PROTECTED]

Re: ?{ } block in regexes?

2005-07-10 Thread Rick Delaney 
On Sat, Jul 09, 2005 at 06:01:20AM +0300, Yuval Kogman wrote:
 How trivial is it to add a ?{ } block that is executed with the
 same semantics as ?{ }, except that instead of running when the
 engine matches over it, it gets run as the engine backtracks over
 it?
 
 my $thing = qr/
   ?{ do_something() }
   ?{ undo_it() }
   $try_this_pattern
 /x;
 
 if $try_this_pattern fails, undo_it() is called to undo
 do_something().

The trivial way:

my $thing = qr/
(?{ $obj = create() }
$try_this_pattern
/x;

sub create  { do_something(); bless [] }
sub DESTROY { undo_it() }

I don't think you'll have to look to hard to find problems with this
approach but most of them will be related to the predictability
of backtracking (due to optimizations, unspecified implementation, etc).
Any addition to the RE engine would likely suffer from the same lack of
predictability so would probably not be much of an improvement over the
above code.

-- 
Rick Delaney
[EMAIL PROTECTED]

?{ } block in regexes?

2005-07-08 Thread Yuval Kogman 
How trivial is it to add a ?{ } block that is executed with the
same semantics as ?{ }, except that instead of running when the
engine matches over it, it gets run as the engine backtracks over
it?

my $thing = qr/
?{ do_something() }
?{ undo_it() }
$try_this_pattern
/x;

if $try_this_pattern fails, undo_it() is called to undo
do_something().

-- 
 ()  Yuval Kogman [EMAIL PROTECTED] 0xEBD27418  perl hacker 
 /\  kung foo master: /me sneaks up from another MIME part: neeyah!



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