Perl’s flip-flop operator, .., (otherwise known as the range operator in scalar context) is a simple way to choose a window on some data. It returns false until its lefthand side is true. Once the lefthand side is true, the flip-flop operator returns true until its righthand side is true. Once the righthand side is true, the flip flop operator returns false. That is, the lefthand side turns it on and the righthand side turns it off. Continue reading “Respect the global state of the flip flop operator”
Month: June 2010
Detect regular expression match variables in your code
[UPDATE: this is not a problem in v5.18 and later.]
In Item 33: “Watch out for match variables”, you found out that the match variable $`, $&, and $` come with a performance hit. With all of the module code that you might use, you might be using those variables even though you didn’t code with them yourself. Continue reading “Detect regular expression match variables in your code”
Effective Perl Programming at YAPC::NA 2010
I’ll be teaching an Effective Perl Programming course at YAPC::NA in Columbus, OH on June 24 and 25 at the conference venue. The cost of the two day master class is just $240, and this year that includes your snacks and lunches each day.
Josh and I will also have a box of signed copies of the book, although those might go fast during the conference (and aren’t part of the course fee). Of course, you can also buy your book in advance and have us sign it during the conference. :)
Know when and when not to write networking code.
Even though Perl has support for low-level socket programming, that doesn’t mean that you have to program at the low-level. For common protocols such as FTP, HTTP, POP3, or SMTP, you can use modules that come with Perl to handle the transport details. libnet, the distribution that comprises the basic protocols, comes with Perl since 5.8. Many other protocols, such as SSH, have implementations on CPAN. You can also install from CPAN many higher level libraries, such as LWP and WWW::Mechanize. Continue reading “Know when and when not to write networking code.”
Use Carp::REPL as an interactive Perl shell.
Wouldn’t it be great if you could stop your program right before it died so you could see what’s causing the problem? You could start the Perl debugger and step your way to the problem, or set up some break points, but that’s often too much work. The Carp::REPL module let’s you drop into a debugger just at the point you need. Continue reading “Use Carp::REPL as an interactive Perl shell.”