Hi, I've been trying to create an extension to be able to use my libaiml library (c++) from within perl. I tried swig, but the class I define in the main header of the library is inside a namespace and swig doesn't support them.

Well, I tried xs afterwards and I quickly got a module that looked it was going to work. I managed to expose the constructor, destructor and 3 other functions. But I don't know how to expose the most important function.

This function takes 2 const std::string& and 1 std::string& where I put my output. The function returns a boolean, indicating success or failure.

What I don't know how to do is how to create a Perl interface for that. I can think of two versions: return a scalar (which would be undef if the function returns false, otherwise it would contain the value written to the third parameter (in C++)). The other version is the closest one to C++: return a scalar (a boolean), take 2 scalars by copy and the last one by reference.

Now... how do I do this? I would like to come up with a C++ solution by writing C++ code, and not fiddling so much with the code below the "MODULE" line on the .xs file.

So, my current xs file is this one:

#ifdef __cplusplus
extern "C" {
#endif

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

#include "ppport.h"

#ifdef __cplusplus
}
#endif

#include <string>
#include <libaiml/core.h>
using std::string;
using aiml::cCore;
using aiml::AIMLError;

class cAiml : public cCore {
  public:
    // Here I could write a function which would call respond()
    // but doing things more Perl Friendly
};

MODULE = AI::AIML               PACKAGE = AI::AIML

cAiml *
cAiml::new()

void
cAiml::DESTROY()

bool
cAiml::initialize(const char* file)

void
cAiml::deinitialize()

long
cAiml::get_error()

const char*
cAiml::get_error_str(AIMLError error_num);
[download]

my typemap:

TYPEMAP
cAiml * O_OBJECT
AIMLError T_ENUM
[download]

the main header of my library:

/*********************************************************************
+******
 *   This file is part of "libaiml"                                   
+     *
 *   Copyright (C) 2005 by V01D                                       
+     *
 *                                                                    
+     *
 *   "libaiml" is free software; you can redistribute it and/or modify
+     *
 *   it under the terms of the GNU General Public License as published
+ by  *
 *   the Free Software Foundation; either version 2 of the License, or
+     *
 *   (at your option) any later version.                              
+     *
 *                                                                    
+     *
 *   "libaiml" is distributed in the hope that it will be useful,     
+     *
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of   
+     *
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the    
+     *
 *   GNU General Public License for more details.                     
+     *
 *                                                                    
+     *
 *   You should have received a copy of the GNU General Public License
+     *
 *   along with "libaiml"; if not, write to the                       
+     *
 *   Free Software Foundation, Inc.,                                  
+     *
 *   59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.        
+     *
 *********************************************************************
+******/

#ifndef __LIBAIML_CORE_H__
#define __LIBAIML_CORE_H__

#define LIBAIML_MAX_LINE_SIZE       16384               // max size a 
+line of text can be (doesn't apply to .aiml files)
#define LIBAIML_POPEN_BUFFER_SIZE               256                   
+  // buffer size used when reading data from popen()

#define LIBAIML_VERSION_STRING  ("libaiml 0.4")
#define LIBAIML_VERSION (0.4)

#include <string>
#include <fstream>
#include <vector>
#include <list>
#include <map>
#include <std_utils/cconfig.h>

#include "global.h"
#include "errors.h"
#include "aiml_parser.h"

namespace _aiml {

class cCore {
  public:
    cCore(void);
    ~cCore(void);

    bool initialize(const std::string& file);
    void deinitialize(void);

    bool respond(const std::string& input, const std::string& username
+, std::string& output);
    void unregister_user(const std::string& user_id);

    AIMLError get_error(void);
    const char* get_error_str(AIMLError error_num);

  private:
    friend class cGraphMaster;
    
    /** Error handling **/
    AIMLError last_error;
    static const char* error_str[AIMLERR_MAX];
    void set_error(AIMLError);

    /** Utility Functions **/
    bool load_substitutions(void);
    bool load_botvars(void);
    void load_aiml_files(void);
    
    void learn_file(const std::string& filename, bool at_runtime = fal
+se);

    bool load_userlist(void);
    void save_userlist(void);

    std::string doSystemCall(const std::string& cmd);
    std::string doJavaScriptCall(const std::string& cmd);

    /** ADD: implement this **/
    bool load_defvars(void);
    const std::string& getBotVar(const std::string& key) const;
    StringMAP botvars_map;
    
    /** Internal modules **/
    cGraphMaster graphmaster;
    AIMLparser aiml_parser;
    
    /** Configuration options/vars **/
    std_util::cConfig cfg;
    
    std::ofstream file_gossip_stream;
    std::string aiml_path, file_substitute, file_gossip, file_botvars,
+ aiml_files, user_dir;
    bool should_trim_blanks, allow_system;

    /** User management **/
    typedef std::map<std::string,_aiml::cUser> UserMap;
    typedef std::list<UserID> UserIDS;
    UserMap user_map;
    UserIDS user_ids;

    bool get_free_uid(UserID* ptr);
};

}

/**
 * Public Interface
 */
namespace aiml {
  using _aiml::cCore;
  using _aiml::AIMLError;
}


#endif  // __LIBAIML_CORE_H__
[download]

It works pretty well like this, just that I can't use respond() with that .xs.

Any help apreciated, I've been googling and reading and man'ning a lot, and can't find anything that clears this for me.