• Code broken by regex fixes in 5.10.0, or, why it's good to help test release candidates

    My baby, ack, broke under Perl 5.10.0, because of a fix in regex behavior that I had been using unknowingly. See, I had always used my regex objects like this:

    my $re = qr/^blah blah/;
    if ( $string =~ /$re/sm )...
    

    when I should have been using it like this:

    my $re = qr/^blah blah/sm;
    if ( $string =~ /$re/ )...
    

    The bug in 5.8.x is that the /$re/sm would incorrectly apply the /sm modifiers to $re. This made the code happen to work, but for the wrong reason. What was especially tricky about finding my bug was that in 5.10.0, the call to /$re/sm ignores the /sm, but doesn't tell you that.

    After some back and forth on p5p, a patch was submitted that gave the warning about the ignored /sm flags, but alas, Perl 5.10 was already out. It wouldn't have been so bad if it hadn't been the day AFTER it was released.

    So, lesson learned: Test your code against new release candidates of Perl, both for your code's sake, AND for Perl's sake.

    And y'know, now that I think of it, this is probably a great policy for Perl::Critic just waiting to happen. I wonder how many other people are doing their regexes the wrong way, too.

  • Perl birthday parties across North America

    Richard Dice writes to tell:

    The Toronto Perl Mongers meet monthly for a combined technical and social meeting -- except in December, when the meeting is purely social. To celebrate the 20th birthday of Perl we scheduled our December 2007 meeting for the 18th. Richard Dice brought a special cake. (It was chocolate, not onion-flavoured as some people feared.) Rough 20 Mongers came out to the event. Fun - and cake! - was had by all. We hope Mongers world-wide enjoy some of the photos taken of the event.

    And on the other side of North America, Andy Sweger writes about the Seattle Perl Mongers' celebration:

    At the regular monthly SPUG meeting on December 18th, 2007, we had a little celebration for Perl's 20th birthday which just happened to be on the same day. We had a lovely cake and we sang happy birthday to Perl for Larry. (Don't mind the bit about Perl 6, Larry. That guy just had too much cake.)
  • Perl 5.10 now available

    Today the Perl Foundation announces the release of Perl 5.10, the first major upgrade to the wildly popular dynamic programming language in over five years. This latest version builds on the successful 5.8.x series by adding powerful new language features and improving the Perl interpreter itself. The Perl development team, called the Perl Porters, has taken features and inspiration from the ambitious Perl 6 project, as well as from chiefly academic languages and blended them with Perl's pragmatic view to practicality and usefulness.

    Significant new language features

    The most exciting change is the new smart match operator. It implements a new kind of comparison, the specifics of which are contextual based on the inputs to the operator. For example, to find if scalar $needle is in array @haystack, simply use the new ~~ operator:

    if ( $needle ~~ @haystack ) ...
    

    The result is that all comparisons now just Do The Right Thing, a hallmark of Perl programming. Building on the smart-match operator, Perl finally gets a switch statement, and it goes far beyond the kind of traditional switch statement found in languages like C, C++ and Java.

    Regular expressions are now far more powerful. Programmers can now use named captures in regular expressions, rather than counting parentheses for positional captures. Perl 5.10 also supports recursive patterns, making many useful constructs, especially in parsing, now possible. Even with these new features, the regular expression engine has been tweaked, tuned and sped up in many cases.

    Other improvements include state variables that allow variables to persist between calls to subroutines; user defined pragmata that allow users to write modules to influence the way Perl behaves; a defined-or operator; field hashes for inside-out objects and better error messages.

    Interpreter improvements

    It's not just language changes. The Perl interpreter itself is faster with a smaller memory footprint, and has several UTF-8 and threading improvements. The Perl installation is now relocatable, a blessing for systems administrators and operating system packagers. The source code is more portable, and of course many small bugs have been fixed along the way. It all adds up to the best Perl yet.

    For a list of all changes in Perl 5.10, see Perl 5.10's perldelta document included with the source distribution. For a gentler introduction of just the high points, the slides for Ricardo Signes' Perl 5.10 For People Who Aren't Totally Insane talk are well worth reading.

    Don't think that the Perl Porters are resting on their laurels. As Rafael Garcia-Suarez, the release manager for Perl 5.10, said: "I would like to thank every one of the Perl Porters for their efforts. I hope we'll all be proud of what Perl is becoming, and ready to get back to the keyboard for 5.12."

    Where to get Perl

    Perl is a standard feature in almost every operating system today except Windows. Users who don't want to wait for their operating system vendor to release a package can dig into Perl 5.10 by downloading it from CPAN, the Comprehensive Perl Archive Network, at http://search.cpan.org/dist/perl/, or from the Perl home page at www.perl.org.

    Windows users can also take advantage of the power of Perl by compiling a source distribution from CPAN, or downloading one of two easily installed binary distributions. Strawberry Perl is a community-built binary distribution for Windows, and ActiveState's distribution is free but commercially-maintained.

    Editor's notes

    For questions, contact Perl Foundation Public Relations at pr@perlfoundation.org.

    Perl:
    perl.org
    Perl is a dynamic programming language created by Larry Wall and first released in 1987. Perl borrows features from a variety of other languages including C, shell scripting (sh), AWK, sed and Lisp. It is distributed with practically every version of Unix available and runs on a huge number of platforms, as diverse as Windows, Mac OS X, Solaris, z/OS, os400, QNX and Symbian.

    Rafael Garcia-Suarez
    email: rgarciasuarez@gmail.com
    Rafael Garcia-Suarez is a French software engineer who lives in Paris, France, and who is currently employed by Booking.com. He has been a contributor to Perl for many years and has stewarded the birth of Perl 5.10 for the last few.

    The Perl Foundation
    perlfoundation.org
    The Perl Foundation is dedicated to the advancement of the Perl programming language through open discussion, collaboration, design, and code. It is a non-profit, 501(c)(3) organization incorporated in Holland, Michigan, USA in 2000.

    This is a copy of the official announcement about Perl 5.10.

  • ActiveState provides Windows binaries of Perl 5.10.0

    ActiveState already has their Perl for Windows available for binary download. I'm sure Strawberry Perl won't be far behind.

  • There is no zeroth century

    From the PostgreSQL date functions reference:

    The first century starts at 0001-01-01 00:00:00 AD, although they did not know it at the time. This definition applies to all Gregorian calendar countries. There is no century number 0, you go from -1 to 1. If you disagree with this, please write your complaint to: Pope, Cathedral Saint-Peter of Roma, Vatican.