[tpm] problems with what regex returns ... in context ?

[Carlo Costantini]

Because I was following along and thought others might be following as well. I thought I would summarize 
what you discovered to help you with this situation.

After looking up $+. I saw that there is also $& which has the string of the last pattern match.

So to summarize:

- a successful match with no captured data 

will have a $& value defined but will not have a $+ value defined.

- a successful match with captured data 

will have both $& and $+ defined but you only need to check $+

- an unsuccessful match

$& will not be defined


Thank you for "thinking aloud", Fulko.

-- 
Carlo


On Friday, 10 May, 2013 at 10:23 AM, Fulko Hew wrote:

> Responding to my own post...
> 
> I just discovered that I can test the defined-ness
> of $+ (the 'last' extraction) because I wasn't sure
> if $1 $2... would be _also_ defined, if I specified a list to return into.
> 
> hmm, yes, $n are populated regardless of the left hand side
> 
> Thanks
> 
> 
> On Fri, May 10, 2013 at 10:16 AM, Mike Stok <mike at stok.ca (mailto:mike at stok.ca)> wrote:
> > My perl is getting a little rusty, but the first thing I thought of was to check the defined-ness of $1 e.g.
> > 
> > my $line = 'this is stuff in here';
> > my @patterns = qw / stuff (stuff) stuff/;
> > foreach $regex (@patterns) {
> > my @capture = ();
> > print "regex is '$regex' ... ";
> > 
> > if ((@capture = ($line =~ m/$regex/)) && defined $1) {
> > print "captured " . scalar @capture . " items \n";
> > my $i = 0;
> > foreach my $item (@capture) {
> > print " capture[$i]: '$item'\n";
> > $i++;
> > }
> > } else {
> > print "nothing captured\n";
> > }
> > } 
> > 
> > 
> > 
> > I'm sure there's some problem with that though...
> > 
> > Mike
> > 
> > On 2013-05-10, at 10:06 AM, Fulko Hew <fulko.hew at gmail.com (mailto:fulko.hew at gmail.com)> wrote:
> > > my $line = 'this is stuff in here';
> > > my @patterns = qw / stuff (stuff) /;
> > > foreach $regex (@patterns) {
> > > my @capture = ();
> > > print "regex is '$regex' ... ";
> > > if (@capture = ($line =~ m/$regex/)) {
> > > print "captured " . scalar @capture . " items \n";
> > > my $i = 0;
> > > foreach my $item (@capture) {
> > > print " capture[$i]: '$item'\n";
> > > $i++;
> > > }
> > > } else {
> > > print "nothing captured\n";
> > > }
> > > }
> > 
> > -- 
> > 
> > Mike Stok <mike at stok.ca (mailto:mike at stok.ca)>
> > http://www.stok.ca/~mike/
> > 
> > The "`Stok' disclaimers" apply.
> 
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