My first guess is abuse of $1.

Why not just call tr/// to count characters?

while (<DATA>) {
    print qq("$_" ),
          tr/ // <= 1 ? "has 1 or no spaces\n"
                      : "has more than one space\n";
}
[download]

You call the regexp engine twice inside each other.

Older perls have problems if you use regexps from inside (?{ }), it seems that the regexp engine is not fully reentrant. If this is not an 5.8.x perl, try upgrading it.

This core dumps on 5.8.3 - I dunno if upgrading can be classed as a solution :-)

Update: Oh, and perlre (on 5.8.3) says:

"(?{ code })"
WARNING: This extended regular expression feature is considered highly experimental, and may be changed or deleted without notice.

I think exploding satisfies the whole "highly experimental" bit.

There is however a simple way of making the code work: you have too many question marks. Try:

print "$_ ", /(.*)(?{$countSpaces->()})/ ? "has 1 or no spaces\n" : "h
+as more than one space\n";
[download]

...in the right place. The output is:

this line has more than one space
 has more than one space
     that_is_5_spaces
 has more than one space
This isonespaceonly
 has more than one space
therearenospaceshere
 has 1 or no spaces
[download]

...which looks like (almost) the right output to me.

Update 2 Erm, ah. Doh. (??{ code }) is perfectly valid according to perlre too - put equally experiment. Nevermind. Using highly experimental features is probably a bad idea.

---

If the information in this post is inaccurate, or just plain wrong, don't just downvote - please post explaining what's wrong.
That way everyone learns.

It still dumps core on bleadperl.

But you can replace the use of regexp for other code.

Thanks gmpassos that was it! I changed my code to this ...

...
use strict;
my $countSpaces = sub {
        my $spaces = tr/ //;
        return qr{(?!)} if $spaces > 1; 
        return qr{(?=)};
};

while (<DATA>) {
        chomp;
        print "$_ [", /(.*)(??{$countSpaces->()})/ ? "OK]\n" : "BAD]\n
+";
}


__DATA__
this line has more than one space
     that_is_5_spaces
This isonespaceonly
therearenospaceshere
[download]




Plankton: 1% Evil, 99% Hot Gas.

I probably would have used something simpler such as:

while (<DATA>) {
   chomp;
   print "'$_' contains ", (@{[/ /g]}) > 1 ?
      "more than one space.\n" :
      "either one space or none.\n";
}

__DATA__
foo bar baz
foobar
foobar baz
foo barbaz
[download]