Tk800.018 patch for possible perl 5.005_63 RE bug

[David Dyck <dcd@tc.fluke.com>]

On Wed, 26 Jan 2000, Nick Ing-Simmons wrote:

> David Dyck <dcd@tc.fluke.com> writes:
> >I didn't look at the archives before I posted the following mail,
> >but do you know what else is known not to work after applying the
> >following patch?
>
> Regular expressions of the form m#(?:^|/)(\w+)#
> i.e. word at start of string or after a /.
> This messes up appname setting, and one or two other things.

Thank you Nick,
  (I've cc'ed p5p - maybe they can add some test cases
   to perl for this)

 I've used Perl since perl version 3, but I've never put
the ^ in the middle like that -- I'm still learning new
things.  (I just searched man perlre, and all the ^ characters
that are not in a range or character class seem to be a the beginning of 
the match, no wait, there is one in the `(?!pattern)' section
but thats the |^, not ^|

Would this alternative re work instead:
    m#^(?:.*/)?(\w+)#

I don't see a test case form
	(?:^|/)(\w+)
     The closest test case where I could find an '|' next to '^' was:
	(^|x)(c)        ca      y       $2      c
     in perl's t/op/re_tests

  Is the failing re you refering to in Tk800.018/Tk/CmdLine.pm as:
    $name = $1 if (($0 =~ m/(?:^|[\/\\])([\w-]+)(?:\.\w+)?$/) && ($1 ne '-e'));
  where $0 is t/widget.t

Here's a test case that matches with older perls (5.005_57),
but doesn't match with 
perl -le '$0="t/widget.t"; $name="unmatched"; 
    $name = $1 if (($0 =~ m/(?:^|[\/\\])([\w-]+)(?:\.\w+)?$/) && ($1 ne "-e")); 
    print "$name";'


  If so I modified the re to hack around  and it passes make test now (w.r.t. widget)
    $name = $1 if (($0 =~ m/^(?:.*[\/\\])?([\w-]+)(?:\.\w+)?$/) && ($1 ne "-e"));


--- ./Tk/CmdLine.pm.orig	Sat Jan 15 04:00:33 2000
+++ ./Tk/CmdLine.pm	Wed Jan 26 10:55:36 2000
@@ -31,7 +31,7 @@
     my $class = ref($this) || $this;
 
     my $name = 'pTk';
-    $name = $1 if (($0 =~ m/(?:^|[\/\\])([\w-]+)(?:\.\w+)?$/) && ($1 ne '-e'));
+    $name = $1 if (($0 =~ m/^(?:.*[\/\\])?([\w-]+)(?:\.\w+)?$/) && ($1 ne '-e'));
 
     my $self = {
         name        => $name,

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Follow-Ups from:

Nick Ing-Simmons <nik@tiuk.ti.com>

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