Perl 5.16 new features, YAPC::Russia «May Perl + Perl Mova» Kiev, 12–13 May 2012

1. Perl 5.16 new features
Perl Mova Kiev, Ukraine
Pavel Vlasov, 2012

2. Content
1.Perl 5.16 coming
2.Unicode features
3.Other features
4.New documentation
5.Performance

3. 1. Perl 5.16 coming
• Development of Perl 5 (1994 – now)
- 18 years
• Release date of Perl 5.16
- 16 may 2012 (in next few days)

4. 1. Perl 5.16 coming
• Perl 5.14 – 14 may 2011
• Perl 5.16 – 16 may 2012
…....
• Perl 5.30 – 30 may 2026
• Perl 5.32 - ?????

5. 2. Unicode features
• fc (fold case)
• quotameta
• unicode_eval
• evalbytes

6. 2. Fold case
• Compare strings non-unicode
uc($string1) eq = uc($string2)
$string1 = ‘A’; $string2 = ‘a’;
uc(‘A’) = A uc(‘a) =A
Result: OK
$string1 = ‘ß’;
uc(‘ß’) = ‘SS’
It’s NOT OK

7. 2. Fold case
• Compare strings in unicode
use feature ‘fc’;
fc($unicode1) eq fc($unicode2)
• Use casefolding
• inside a double-quoting string - "F$variable"

8. 2. quotameta
• In Perl 5.16 adopted a Unicode-defined strategy for quoting
non-ASCII characters
my $string = ‘Perl May 2011 in Moscow';
my $substr = ‘May.*?Moscow';
$string =~ s{Q$substrE}{Mova 2012 in Kiev};
• Or:
use feature ‘unicode_strings’;
my $string = ‘Perl May 2011 in Moscow';
my $substr = ‘May.*?Moscow';
my $quoted_substr = quotemeta($substr);
$string =~ s{$quoted_substr}{Mova 2012 in Kiev};

9. 2. unicode_eval, evalbytes
unicode_eval default feature of Perl 5.16
eval – evaluate string of characters
evalbytes – die if the string contains any
characters outside the 8-bit range

10. 3. Other features
• current sub __SUB__
• CORE namespace
• array base
• debugger

11. 3. Current sub
• current_sub (__SUB__) - reference to the current
subroutine or undef outside of subroutine
• easier to write recursive closures.
use feature ‘current_sub’;
sub closure {
my $init = shift;
return sub {
state $counter = $init;
return if $counter++ > 10;
__SUB__->();
}
}

12. 3. CORE Namespace
• Namespace for Perl’s core routines
• Give access to the original built-in of Perl
use v5.16;
or
use feature ‘say’;
or
CORE::say “yes”;

13. 3. array base
• special variable for array base
• The 'array_base' feature replace variable $[
• $[ affected also string not only arrays
use feature ‘array_base’;
$[ = 1;

14. 3. debugger
• Tracing mode (t command) accept number of
subroutine for trace
• Breakpoints with file names
$ b [file]:[line] [condition]
$ b lib/MyModule.pm:237 $x > 30

15. 4. New documentation
• perldtrace
• perlexperiment
• perlootut
• perlxstypemap

16. 5. Performance
Improved performance for Unicode
properties in regexp
local $_ is faster now
More? perl5160delta.pod

17. Used resources
• Perl5160delta.pod
• www.effectiveperlprogramming.com
• Mailing list of p5p

18. Thank you for attention!
paul.vlasov@gmail.com