Category Archives: 5.14

Enforce ASCII semantics when you only want ASCII

When Perl made regexes more Unicode aware, starting in v5.6, some of the character class definitions and match modifiers changed. What you expected to match \d, \s, or \w are more expanvise now (

Don’t use auto-dereferencing with each or keys

Perl 5.14 added an auto-dereferencing features to the hash and array operators, and I wrote about those in Use array references with the array operators. I’ve never particularly liked that feature, but I don’t have to like everything. Additionally, Perl 5.12 expanded the job of keys and values to also work on arrays.

Set default regular expression modifiers

Are you tired of adding the same modifiers to all of your regular expressions? For instance, if you might always add the /u modifier to turn on Unicode semantics on all of your patterns, including qr//, m//, and s///. Instead of remembering to do that to every pattern, the re that ships with Perl 5.14 […]

Perl 5.14 adds non-destructive transliteration

[This is a mid-week bonus item since it's so short] In Perl 5.13.2, you got a non-destructive version of the substitution operator (Use the /r substitution flag to work on a copy). Instead of changing it’s target, the non-destructive version returns a new string that has the substitution. Perl 5.13.7 extends the /r to work […]

Use array references with the array operators

There’s a significant change in syntax showing up in Perl 5.14. The array operators push, pop, shift, and unshift previously only worked on named arrays or dereferenced references. Now, thanks to David Golden, they’ll work on array references. Not only that, they’ll work on references that you’ve stored in variables or that come as the […]

Use the return value from srand

[This is another bonus, mid-week item since it's so short and probably mostly useless as a tweak to what you already do.] Perl 5.14 changes srand to return the seed that it used to start the pseudorandom number generator that gives you numbers through rand. There are plenty of interwebs that will explain the difference […]

Let perl create your regex stringification

Perl 5.14 changes how regular expression objects stringify. This might not seem like a big deal at first, but it exposes a certain sort of bug that you may have never considered. It even broke several modules on CPAN. If you previously tested for hard-coded stringifications of patterns, Perl 5.14 is probably going to break […]

Specify any character by its octal ordinal value.

Perl 5.14 gives you some new ways to represent characters so you can avoid some annoying and ambiguous interpolations. Not only that, the new syntax unifies the different ordinal representations so you can specify characters using the same syntax even if you want to use different bases. This feature was added in Perl 5.13.3, in […]

Use the return value of given

Perl 5.14, when it’s released, allows you to use a return value from given-when. You have to wrap it in a do (Item 25: Use do {} to create inline subroutines): use 5.013; my $value = do { given ( $ARGV[0] ) { when( /^\p{N}+\z/ ) { ‘digits’ } when( /^\p{L}+\z/ ) { ‘alphabetics’ } […]

Use the /r substitution flag to work on a copy

How many times has this happened to you? You want to modify each element of an array so you send it through a map (Item 20. Use foreach, map, and grep as appropriate.). However, instead of your expected output, you only to get a bunch of numbers or empty strings back? For example, in this […]