Perl defines two internal pseudo-signals that you can trap. There’s one for die, which I covered in and eventually told you not to use. There’s also one for warn that’s quite safe to use when you need to intercept warnings. To catch a warning, you set a signal handler for the __WARN__ pseudo-signal. The underscores [...]
Perl actually has two encodings that get the letters u, t, f, and 8. One will happily let you do bad things, and the other will let you do bad things but with a warning that you can make fatal. There’s an encoding layer with the name :utf8 and there’s the encoding name UTF-8 that [...]
Normally, you shouldn’t have to care about a string’s encoding. Indeed, the abstract string has no encoding. It exists as an idea without a representation and it’s not until you want to put it on disk, send it down a pipe, or otherwise force it to exist as electrical pulses, magnetic pole orientation, and so [...]
Create Task distributions A Task distribution is like a normal Perl distribution in structure, but it doesn’t actually provide any code. It lists as pre-requisites all of the modules or distributions that you want to install so you can use a conventiional CPAN tool to install all of the dependencies. A Task is slightly different [...]
In the earlier Item, Understand the Test Anywhere Protocal (TAP), you saw the very basics of that simple, line-oriented test report. You ran a single test and it output a single line to denote the status of the test, and possibly some diagnostic information. The TAP, however, didn’t organize any of the tests for you. [...]
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. The autovivification pragma, which you can get from CPAN, lets you decide how autovivification works, or doesn’t [...]
If you are playing with Unicode, you’re probably going to want to convert to the various normalization forms. There are some programs to do this in the Unicode::Tussle distribution, but you can also create some one-liners to do this as well (Item 120. Use Perl one-liners to create mini programs). If you want to read [...]
The perl interpreter is getting much better with its Unicode support, but that doesn’t mean everything just works because most of the code you probably are about is in modules, which might not have kept up. Some of this becomes apparent when you give another module some Unicode strings for it to output. For instance, [...]
Unicode character ranges have the same gotchas as the ASCII character ranges, although they become more apparent and more important. You’re probably used to creating a range for all the letters, like the character classes [A-Z] or [a-z], the range ‘a’ .. ‘z’, or the range in a transliteration, and not having a problem. If [...]
Perl 5.16 makes the Perl special variable, $$, writeable, but with some magic. That’s the variable that holds the process ID. Why would you ever want to do that? There’s not much to write about with this new feature, but there’s plenty to write against it since it introduces more magic (see commit 9cdac2 on [...]
