I'm utilizing WWW::Mechanize to get a page and return the content of that page, and then in a different instance of the script, submit a form on that same page with the original session. The way I intended to do this was to store the mech object via Storable or YAML in the first instance, then retrieve the mech object in the second instance.

Note: for the purpose of these tests, I'm requesting to "http://localhost/mech-form.php" which is just a page with a form that submits to itself and prints out its current session id.

use strict;
use WWW::Mechanize;
use Storable qw(store retrieve freeze thaw);

# init a mech instance
my $mech = WWW::Mechanize->new();

# on first instance...
if(! -f 'stored_mech.dat') {
    # create, get, freeze, and store
    $mech->get('http://localhost/mech-form.php');
    store([freeze($mech)], 'stored_mech.dat');
    exit;
}
# on subsequent instance...
else {
    # retrieve, thaw, and submit form
    my $stored = retrieve('stored_mech.dat');
    $mech = thaw($stored->[0]);
    $mech->submit_form(form_number=>1);
}
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Storable dies complaining that it can't store CODE items, so I'm using YAML's freeze/thaw and DumpFile/LoadFile instead:

use strict;
use WWW::Mechanize;
use YAML qw(DumpFile LoadFile freeze thaw);

# init a mech instance
my $mech = WWW::Mechanize->new();

# on first instance...
if(! -f 'stored_mech.dat') {
    # get, freeze, and store
    $mech->get('http://localhost/mech-form.php');
    DumpFile('stored_mech.dat', [freeze($mech)]);
    exit;
}
# on subsequent instance...
else {
    # retrieve, thaw, and submit form
    my $stored = LoadFile('stored_mech.dat');
    $mech = thaw($stored->[0]);
    $mech->submit_form(form_number=>1);
}
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But after I load the mech object and try to submit the form, I get the following error:

Can't locate object method "scheme" via package "URI::http" at /usr/sh
+are/perl5/URI.pm line 52.
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I decided to try and save/load the cookies as well. That way, after I load the mech object, I can re-get the page, then just reload the saved cookie jar which should continue the same session

use strict;
use WWW::Mechanize;
use YAML qw(DumpFile LoadFile freeze thaw);

# init a mech instance
my $mech = WWW::Mechanize->new(cookie_jar => {ignore_discard => 0}); #
+ save even browser-lifetime cookies

# on first instance...
if(! -f 'stored_mech.dat') {
    # get, freeze, save cookie jar, and store
    $mech->get('http://localhost/mech-form.php');
    $mech->cookie_jar->save('cookies.dat');
    DumpFile('stored_mech.dat', [freeze($mech)]);
    exit;
}
# on subsequent instance...
else {
    # retrieve, thaw
    my $stored = LoadFile('stored_mech.dat');
    $mech = thaw($stored->[0]);
    # re-get page and reload cookies
    $mech->get('http://localhost/mech-form.php');
    $mech->cookie_jar->clear();
    $mech->cookie_jar->load('cookies.dat');
    # submit form with (presumably) original session
    $mech->submit_form(form_number=>1);
}
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However, it seems like it's still using a new session after i reload the cookie jar, which I confirmed by dumping the response headers and page content (which contains the server-side session id):

use strict;
use WWW::Mechanize;
use YAML qw(DumpFile LoadFile freeze thaw);

# init a mech instance
my $mech = WWW::Mechanize->new(cookie_jar => {ignore_discard => 0}); #
+ save even browser-lifetime cookies

# on first instance...
if(! -f 'stored_mech.dat') {
    # get, freeze, save cookie jar, and store
    $mech->get('http://localhost/mech-form.php');
    $mech->cookie_jar->save('cookies.dat');
    printf "Before freeze & save: \%s\n\n", $mech->response()->headers
+()->as_string();
    printf "Page session id: \%s\n\n", $mech->content();
    DumpFile('stored_mech.dat', [freeze($mech)]);
    exit;
}
# on subsequent instance...
else {
    # retrieve, thaw
    my $stored = LoadFile('stored_mech.dat');
    $mech = thaw($stored->[0]);
    # re-get page and reload cookies
    $mech->get('http://localhost/mech-form.php');
    $mech->cookie_jar->clear();
    $mech->cookie_jar->load('cookies.dat');
    # submit form with (presumably) original session
    $mech->submit_form(form_number=>1);
    printf "After thaw & submit: \%s\n", $mech->response()->headers()-
+>as_string();
    printf "Page session id: \%s\n\n", $mech->content();
}
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This results in the output below (after I've stripped the page's markup and the non-related headers):

~$ perl ./mech-test.pl
Before freeze & save: Set-Cookie: PHPSESSID=p9ogedv2qf1r5h664la79is1j2
+; path=/

Page session id: p9ogedv2qf1r5h664la79is1j2 

~$ perl ./mech-test.pl
After thaw & submit: Set-Cookie: PHPSESSID=tq3devkvch2t5fsq6qbp707de4;
+ path=/

Page session id: tq3devkvch2t5fsq6qbp707de4
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So even after clearing and reloading the cookie jar, it's not keeping the same session across multiple instances of this script...and I have no clue where to go from here. Is there something I'm missing? Am I going to have to go mucking about in the Mechanize internals?