The Test Anything Protocol, or just TAP, is the formalization of Perl 5’s test structure from the Test::Harness module. Either Andreas König or Tim Bunce (they don’t remember which one of them did it) created the module, but they can’t remember who did what or when. The Changes file for the Test-Harness starts in seriousness in 2006, around the time that people started working on the next generation of Perl’s testing backend, despite it existing for several years before that. Now TAP is semi-formalized (and IETF RFC is in the works) and has it’s own website at testanything.org. Continue reading “Understand the Test Anything Protocol”
Category: chapters
Pass the empty subclass test
Is your object-oriented module subclassable? Do you know that from testing or are you just guessing? Setting aside other Perl programmers reaching into your package and redefining your subroutines, there are some basic things you can do to ensure that you’ve made life unhard for the people you want to extend your classes. Continue reading “Pass the empty subclass test”
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”
Understand autovivification
Perl will autovivify complex data structures when you use them as if they already exist. This feature saves you a lot of annoying work defining structures that you intend to use. However, this also means that Perl might create data structures that you don’t intend to use in code that isn’t just assigning values. Continue reading “Understand autovivification”
Read a few lines from a file
How would you get more than one line from a file? In the original Effective Perl blog that Joseph set up to support the first edition of Effective Perl Programming, he shows two possible techniques. One uses a foreach: Continue reading “Read a few lines from a file”
Know the two different forms of eval
Perl’s eval leads a double life, and, like Dr. Jekyl and Mr. Hyde, one is dangerous and one is almost safe. And, it’s important to know which one is dangerous; I grew up thinking that Dr. Jekyl was the bad one because evil people, such as Dr. No, had titles.
You can recognize the evals by their first, and only, argument. One form takes a string and the other takes a block. The string version compiles a string as Perl code and executes its, all at runtime. The block form runs, at run time, code that perl has already compiled. Continue reading “Know the two different forms of eval”
Know the phases of a Perl program’s execution
There are two major phases in the execution of a program run by Perl, which you sometimes see as “compile time” and “run time”, or sometimes now, “compile phase” and “run phase”. In the broadest of strokes, perl compiles code in the compile phase, and when it’s completely done with that, it moves on to the run phase, where it executes the code that it completely compiled. Continue reading “Know the phases of a Perl program’s execution”
Use Test::More as you experiment
When you’re trying something new, write small programs to test the idea or the new feature. This way, you isolate what you’re doing from the rest of the big application where you might want to use the idea. Some people try to insert the new features directly into the middle of their large programs, but then have problems separating the bugs from the rest of the application with the new thing they want to add. Continue reading “Use Test::More as you experiment”
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”
Find dates with Regexp::Common
[This is a mid-week bonus item]
Suppose you want to find some dates inside a big string. The problem with dates is that there are some many ways to write them, and even if you can come up with a pattern to get the structure right, can you handle the different locales and languages that use different words to refer to the same day or month? Continue reading “Find dates with Regexp::Common”