Thanks to the help from the wise monks here, (see A few very basic questions about Extending Perl), I have made slow but steady progress in writing XS routines. As mentioned there, I want to integrate a C Library (whose shared object is available but not the source) to manage sessions. Everything works as I want, except for a lurking suspicion that being a noob, I have left out something important :)

Here is the standalone XSUB that essentially mimics the C Library that I want to integrate. I have implemented only 3 of the important functions here — a function that allocates some space and sends me a handle to that space (perl sees the pointer to a struct cast to integer); a function that gets the variables of that struct; and finally a function that frees the allocated space when my session is over. I need to pass the handle (an int in perl) to access each function in the Library. Of course this is only a sample implementation of what the C-library provides with all the other parameters removed:

#include "EXTERN.h"
#include "perl.h"
#include "XSUB.h"

#include "ppport.h"

typedef struct {
    int id;
    int desc;
    char* str;
} session;

MODULE = MySession        PACKAGE = MySession

void
new(str)
    char* str

    PREINIT:
        session* tmppt;
        int tmpint;
    PPCODE:
        tmppt = (session*) malloc(sizeof(session));
        tmppt->id = 42;
        tmppt->desc = 4242;
        tmppt->str = str;
        tmpint = (int) tmppt;

        EXTEND(SP, 1);
        PUSHs(sv_2mortal(newSViv((int) tmppt)));

MODULE = MySession        PACKAGE = MySession        

void
get(hndl)
    int hndl

    PREINIT:
        session* tmppt;
    PPCODE:
        tmppt = (session *)hndl;
        EXTEND(SP, 3);
        PUSHs(sv_2mortal(newSViv(tmppt->id)));
        PUSHs(sv_2mortal(newSViv(tmppt->desc)));
        PUSHs(sv_2mortal(newSVpv(tmppt->str, 0)));

MODULE = MySession        PACKAGE = MySession

void
disconnect(hndl)
    int hndl
    
    CODE:
        free((session*) hndl);
[download]

And here is a test file for the routines:

#!/usr/bin/env perl

use strict;
use warnings;

use ExtUtils::testlib;

use MySession;

my $x = MySession::new("Session ID Goes Here");
print "$x\n";
my ($p, $q, $str) = MySession::get($x);
print "$p\n$q\n$str\n";

my $y = MySession::new("Another Session ID Goes Here");
print "$y\n";
($p, $q, $str) = MySession::get($y);
print "$p\n$q\n$str\n";

my $z = MySession::new("Yet Another Session ID Goes Here");
print "$z\n";
($p, $q, $str) = MySession::get($z);
print "$p\n$q\n$str\n";

MySession::disconnect($x);
MySession::disconnect($y);
MySession::disconnect($z);
 __END__
[download]

Now for the questions:

1. The session struct contains a pointer to a string. This string is passed from the Perl code. I am assuming that perl will free string so I do not specifically free the memory associated with the string. I just free the memory associated with the struct as a whole. Is this correct?
2. I want to now use the functions implemented here as methods in a Moose class. I can always define a module (as I have done here) say MySession and "use" this class in my Moose class and thereby access those functions. But surely there must be a better way? Can you help me with integrating this XSUB concisely with my Moose class or direct me to documentation on how this can be achieved?
3. Finally, any pointers on improving the XSUB itself (as implemented here) and the test script would be great.

Thank you once again for your patience and your wisdom

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