Perl 学习手札之十六： New features in Perl 5.10

Using Perl 5.10 features

perl 5.10 includes new language features

 incompatible with previous version

use feature ':5.10';

use feature qw(switch say state);

use 5.010

say feature.

#!/usr/bin/perl
#
use strict;
use warnings;
use feature ":5.10";

main(@ARGV);

sub main
{
    say "This is the Perl 5.10 new features exercise file.";
    say "this is another line";
}

sub error
{
    my $e = shift || 'unkown error';
    my $me = ( split(/[\\\/]/, $0 ) )[-1];
    print("$me: $e\n");
    exit 0;
}

switch feature:

switch.pl

#!/usr/bin/perl
#
use strict;
use warnings;
use feature ":5.10";

main(@ARGV);

sub main
{
    my $s='jimi hendrix';#5
    given($s){
        when(undef){say'$s is undefined'}
        when('jimi'){say'$s is musician'}
        when(/jimi/){say'$s maybe a muscian'}
        when([1,3,5,7,9]){say'$s is odd number'}
        default{say '$s is something else!'}
    }
}

sub error
{
    my $e = shift || 'unkown error';
    my $me = ( split(/[\\\/]/, $0 ) )[-1];
    print("$me: $e\n");
    exit 0;
}

state feature;

state.pl

#!/usr/bin/perl
#
use strict;
use warnings;
use feature ":5.10";

main(@ARGV);

sub main
{
    my $i = 5;
    increment($i);
    increment($i);
    increment($i);
    increment($i);
}

sub increment{
    state $n = shift;
    say ++$n;
}

sub error
{
    my $e = shift || 'unkown error';
    my $me = ( split(/[\\\/]/, $0 ) )[-1];
    print("$me: $e\n");
    exit 0;
}

注意此时的state关键字，如果用my替换，运行结果会不同！

到此为止，Perl学习手札的更新，告一段落。进阶更新待定