Can this be done?

This is Perl, of course it can be done. In this particular case, we need to avail ourselves of demerphq's most excellent Data::Dump::Streamer.

Even then, a major imposition is that you have to use package variables, since lexical variables can't be injected into scope from an eval.

You can take your data structure and dump it out, being careful to name it so that you can find it again:

use strict;
use warnings;

use Data::Dump::Streamer;

use vars qw($hash $var1 $var2);

$hash->{subs}->[0] = sub {
    $var1 = "a";
    $var2 = "b";
};

$hash->{subs}->[1] = sub {
    $var1 = "c";
    $var2 = "d";
};

Dump($hash)->Names('$hash')->Out;

[download]

This writes the sub to STDOUT. You will probably want to write it to a filehandle; read the documentation to find out how to do that.

You can then thaw the subroutines by eval'ing the resulting dumped code:

use strict;
use warnings;

use vars qw($hash $var1 $var2);

my $file = shift or die "No file given\n";
open my $in, '<', $file or die "input $file: $!\n";

eval do {
    local $/ = undef;
    <$in>;
};

$var1 = 'foo';

print "var1 = $var1\n";
$hash->{subs}[1]->();
print "var1 = $var1\n";

[download]

You will observe that $var1 changes its value after calling the subroutine. Be that as it may, this is a pretty odd thing to want to do. If it's not impolite, I'm curious to know what you want to use it for.

• another intruder with the mooring in the heart of the Perl

In reply to Re: Saving sub routines.. Is it possible? by grinder
in thread Saving sub routines.. Is it possible? by cosmicperl

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