Dependency of nagios-plugins-nwc-health-8.0-1.1.src.rpm

Name: perl-Lexical-Persistence

Project: openSUSE_13.2

Repository: oss

Title: Persistent lexical variable values for arbitrary calls.

Description:
Lexical::Persistence does a few things, all related. Note that all the
behaviors listed here are the defaults. Subclasses can override nearly
every aspect of Lexical::Persistence's behavior.

Lexical::Persistence lets your code access persistent data through lexical
variables. This example prints "some value" because the value of $x
persists in the $lp object between setter() and getter().

use Lexical::Persistence;

my $lp = Lexical::Persistence->new();
$lp->call(\&setter);
$lp->call(\&getter);

sub setter { my $x = "some value" }
sub getter { print my $x, "\n" }

Lexicals with leading underscores are not persistent.

By default, Lexical::Persistence supports accessing data from multiple
sources through the use of variable prefixes. The set_context() member sets
each data source. It takes a prefix name and a hash of key/value pairs. By
default, the keys must have sigils representing their variable types.

use Lexical::Persistence;

my $lp = Lexical::Persistence->new();
$lp->set_context( pi => { '$member' => 3.141 } );
$lp->set_context( e => { '@member' => [ 2, '.', 7, 1, 8 ] } );
$lp->set_context(
animal => {
'%member' => { cat => "meow", dog => "woof" }
}
);

$lp->call(\&display);

sub display {
my ($pi_member, @e_member, %animal_member);

print "pi = $pi_member\n";
print "e = @e_member\n";
while (my ($animal, $sound) = each %animal_member) {
print "The $animal goes... $sound!\n";
}
}

And the corresponding output:

pi = 3.141
e = 2 . 7 1 8
The cat goes... meow!
The dog goes... woof!

By default, call() takes a single subroutine reference and an optional list
of named arguments. The arguments will be passed directly to the called
subroutine, but Lexical::Persistence also makes the values available from
the "arg" prefix.

use Lexical::Persistence;

my %animals = (
snake => "hiss",
plane => "I'm Cartesian",
);

my $lp = Lexical::Persistence->new();
while (my ($animal, $sound) = each %animals) {
$lp->call(\&display, animal => $animal, sound => $sound);
}

sub display {
my ($arg_animal, $arg_sound);
print "The $arg_animal goes... $arg_sound!\n";
}

And the corresponding output:

The plane goes... I'm Cartesian!
The snake goes... hiss!

Sometimes you want to call functions normally. The wrap() method will wrap
your function in a small thunk that does the call() for you, returning a
coderef.

use Lexical::Persistence;

my $lp = Lexical::Persistence->new();
my $thunk = $lp->wrap(\&display);

$thunk->(animal => "squirrel", sound => "nuts");

sub display {
my ($arg_animal, $arg_sound);
print "The $arg_animal goes... $arg_sound!\n";
}

And the corresponding output:

The squirrel goes... nuts!

Prefixes are the characters leading up to the first underscore in a lexical
variable's name. However, there's also a default context named underscore.
It's literally "_" because the underscore is not legal in a context name by
default. Variables without prefixes, or with prefixes that have not been
previously defined by set_context(), are stored in that context.

The get_context() member returns a hash for a named context. This allows
your code to manipulate the values within a persistent context.

use Lexical::Persistence;

my $lp = Lexical::Persistence->new();
$lp->set_context(
_ => {
'@mind' => [qw(My mind is going. I can feel it.)]
}
);

while (1) {
$lp->call(\&display);
my $mind = $lp->get_context("_")->{'@mind'};
splice @$mind, rand(@$mind), 1;
last unless @$mind;
}

sub display {
my @mind;
print "@mind\n";
}

Displays something like:

My mind is going. I can feel it.
My is going. I can feel it.
My is going. I feel it.
My going. I feel it.
My going. I feel
My I feel
My I
My

It's possible to create multiple Lexical::Persistence objects, each with a
unique state.

use Lexical::Persistence;

my $lp_1 = Lexical::Persistence->new();
$lp_1->set_context( _ => { '$foo' => "context 1's foo" } );

my $lp_2 = Lexical::Persistence->new();
$lp_2->set_context( _ => { '$foo' => "the foo in context 2" } );

$lp_1->call(\&display);
$lp_2->call(\&display);

sub display {
print my $foo, "\n";
}

Gets you this output:

context 1's foo
the foo in context 2

You can also compile and execute perl code contained in plain strings in a
a lexical environment that already contains the persisted variables.

use Lexical::Persistence;

my $lp = Lexical::Persistence->new();

$lp->do( 'my $message = "Hello, world" );

$lp->do( 'print "$message\n"' );

Which gives the output:

Hello, world

If you come up with other fun uses, let us know.

Version: 1.023

Release: 2.1.3

Architecture: noarch

Size: 29.4 KB

Build Time: 2014-10-06 17:42:01 +0200 (over 9 years ago)