Not sure which loop you want to break out of? Perl v5.18 makes that easy with computed labels. The value you give next, last, and redo no longer has to be a literal. You could already do this with goto, but now you can give the loop controllers an expression. Continue reading “Use a computed label with loop controllers”
Category: miscellany
In v5.20, -F implies -a implies -n
Perl was once known for its one-liners in its sysadmin heydays. People would pass around lists of these one liners, many of which replaced complicated pipelines that glued together various unix utilities to do some impressive system maintenance. Continue reading “In v5.20, -F implies -a implies -n”
Declare packages outside of their block
Perl v5.14 gets a step closer to a saner way to declare classes with its new package NAME BLOCK syntax that lets you easily group everything that goes in a package. Continue reading “Declare packages outside of their block”
The Perl 5.12 yada yada operator
Perl v5.12 adds a placeholder operator, ..., called the yada yada operator, after an episode of Seinfeld where the interesting parts of the story are replaced with “yada yada yada”. Continue reading “The Perl 5.12 yada yada operator”
Create your own dualvars
Perl’s basic data type is the scalar, which takes its name from the mathematical term for “single item”. However, the scalar is really two things. You probably know that a scalar can be either a number or a string, or a number that looks the same as its string, or a string that can be a number. What you probably don’t know is that a scalar can be two separate and unrelated values at the same time, making it a dualvar. Continue reading “Create your own dualvars”
Turn off autovivification when you don’t want it
Autovivification, although a great feature, might bite you when you don’t expect it. I explained this feature in Understand autovivification, but I didn’t tell you that there’s a way to control it and even turn it off completely. Continue reading “Turn off autovivification when you don’t want it”
Set the line number and filename of string evals
Errors from a string eval can be tricky to track down since perl doesn’t tell you where the eval was. It treats each of the string evals as a separate, virtual file because it doesn’t remember where the string argument came from. Since perl compiles that during the run phase (see Know the phases of a Perl program’s execution), the information the compiler dragged along for filenames and line numbers is so longer around. Continue reading “Set the line number and filename of string evals”
Override die with END or CORE::GLOBAL::die
Perl lets you override the effects of warn and die by redefining the signals that Perl sends when you call those functions. You probably don’t want to use the signal from die, though, since it might mean a couple of different things. Continue reading “Override die with END or CORE::GLOBAL::die”
Use Git::CPAN::Patch to make quick patches to CPAN distributions
The Git distributed version control system is very popular in with Perlers, and even if you aren’t using it for your own project, you should know how to do simple things with it so you can interact with the most active parts of the community. It’s not that hard. Not only that, many Perl projects are on Github, and it’s something else you’ll know when you go to your next interview. Continue reading “Use Git::CPAN::Patch to make quick patches to CPAN distributions”
Choose the right Perl version for you
When you’re paying attention to the Perl news about new Perl releases, you need to know which ones matter to you. It seems like a simple question, but there are many things to consider. Do you use an experimental or stable release? In a stable release, which of the supported versions should you use? What does your vendor provide? What does your manager let you use? Continue reading “Choose the right Perl version for you”