I have a Perl program that generates parsing rules as subs from an input file. The subs are anonymously defined an put into a hash. Now, I want to export that hash, with all the subs and then load them again later to use with a different program.
How do I go about doing this? Is there some way to extract the code of each sub, or can I copy the block of memory that the hash exists in and then cast it as a hash when I load it again later?
Thanks in advance.
From the "Code References" section of the Storable documentation (with added emphasis):
Since Storable version 2.05, CODE references may be serialized with the help of
B::Deparse
. To enable this feature, set$Storable::Deparse
to a true value. To enable deserialization,$Storable::Eval
should be set to a true value. Be aware that deserialization is done througheval
, which is dangerous if the Storable file contains malicious data.
In the demo below, a child process creates the hash of anonymous subs. Then the parent—in an entirely separate process and address space, so it can't see %dispatch
—reads the output from freeze
in the same way that you might from a file on disk.
#! /usr/bin/perl
use warnings;
use strict;
use Storable qw/ freeze thaw /;
my $pid = open my $fh, "-|";
die "$0: fork: $!" unless defined $pid;
if ($pid == 0) {
# child process
my %dispatch = (
foo => sub { print "Yo!\n" },
bar => sub { print "Hi!\n" },
baz => sub { print "Holla!\n" },
);
local $Storable::Deparse = 1 || $Storable::Deparse;
binmode STDOUT, ":bytes";
print freeze \%dispatch;
exit 0;
}
else {
# parent process
local $/;
binmode $fh, ":bytes";
my $frozen = <$fh>;
local $Storable::Eval = 1 || $Storable::Eval;
my $d = thaw $frozen;
$d->{$_}() for keys %$d;
}
Output:
Hi! Holla! Yo!