Effective Perl Programming – write better, more idiomatic Perl
This is a chapter in Perl New Features, a book from Perl School that you can buy on LeanPub or Amazon. Your support helps me to produce more content.
Perl v5.36 automatically turns on warnings when you specify the minimum Perl version with use:
use v5.36; # use warnings for free
Since this form has been turning on strictures since v5.12 (Implicitly turn on strictures with Perl 5.12), you no longer have to specify warnings or strict at the top of my program.
Before Perl v5.10 introduced state variables, people did various things to create persistent lexical variables for a subroutine. With v5.30, one of those constructs is now a fatal error.
Often you want a persistent variable to be scoped and private to a subroutine. But, once you leave that scope, normal lexical variables disappear because their reference count drops to zero. So, no persistence.
Continue reading “No more false postfix lexical declarations in v5.30”
Perl v5.28 will have better deprecation warnings. Most of this I picked up from the lightning talk that Abigail gave at The Perl Conference. Continue reading “Deprecation warnings now tell you when the features will disappear”
Perl 5.18 provides a new way to introduce experimental features in a program, augmenting the feature pragma that v5.10 added. This change marks certain broken v5.10 features as experimental with an eye toward possible removal from the language.
Smart matching in v5.10 led to several broken and conflated features. The given used a lexical version of $_, which broke many other common uses of that variable inside the given, which I explain in Use for() instead of given() and you can see in given/when and lexical $_ …. Continue reading “Experimental features now warn (reaching back to v5.10)”