Accessing C structures in Ruby

ruby-talk
1

(I've already looked at Swig, btw. I'd like to do this one by hand.)

I have the following:

typedef struct {
  double x;
  double y;
  double z;
} VelocityRecord;

typedef struct {
  double x;
  double y;
  double z;
} PositionRecord;

typedef struct {
  int id;
  int type;
  PositionRecord position;
  VelocityRecord velocity;
} Player;

Player Players[10];

The number of Players is fixed ahead of time. I want to be able to
access that data from Ruby. Ideally, something like:

module Simulation
    attr_accessor :players # Other stuff will be here
    class Player
        class VelocityRecord
            attr_accessor :x, :y :z
        end
        class PositionRecord
          attr_accessor :x, :y, :z
        end
    end
end

2

Hm, on second thought, it's probably a lot easier to do:

class Player
  attr_reader :x_position, :y_position, :z_position, :x_velocity,
:y_velocity, :z_velocity
end

So, maybe something like this?

void Init_Simulation()
{
  rb_define_module(mSimulation, "Simulation");
  rb_define_class_under(cPlayer, "Player");

  rb_define_method(cPlayer, "x_position", get_x_position, 0);
  rb_define_method(cPlayer, "y_position", get_y_position, 0);
  rb_define_method(cPlayer, "z_position", get_z_position, 0);
  rb_define_method(cPlayer, "x_velocity", get_x_velocity, 0);
  rb_define_method(cPlayer, "y_velocity", get_y_velocity, 0);
  rb_define_method(cPlayer, "z_velocity", get_z_velocity, 0);
}

···

On 12/12/05, Joe Van Dyk <joevandyk@gmail.com> wrote:

(I've already looked at Swig, btw. I'd like to do this one by hand.)

I have the following:

typedef struct {
  double x;
  double y;
  double z;
} VelocityRecord;

typedef struct {
  double x;
  double y;
  double z;
} PositionRecord;

typedef struct {
  int id;
  int type;
  PositionRecord position;
  VelocityRecord velocity;
} Player;

Player Players[10];

The number of Players is fixed ahead of time. I want to be able to
access that data from Ruby. Ideally, something like:

module Simulation
    attr_accessor :players # Other stuff will be here
    class Player
        class VelocityRecord
            attr_accessor :x, :y :z
        end
        class PositionRecord
          attr_accessor :x, :y, :z
        end
    end
end

3

Joe Van Dyk wrote:

(I've already looked at Swig, btw. I'd like to do this one by hand.)

I have the following:

typedef struct {
  double x;
  double y;
  double z;
} VelocityRecord;

typedef struct {
  double x;
  double y;
  double z;
} PositionRecord;

typedef struct {
  int id;
  int type;
  PositionRecord position;
  VelocityRecord velocity;
} Player;

Player Players[10];

The number of Players is fixed ahead of time. I want to be able to
access that data from Ruby. Ideally, something like:

module Simulation
    attr_accessor :players # Other stuff will be here
    class Player
        class VelocityRecord
            attr_accessor :x, :y :z
        end
        class PositionRecord
          attr_accessor :x, :y, :z
        end
    end
end

My typical recommendation is to just wrap a pointer to
the struct and pass that around. Then, for each method
just extract the pointer, access the correct field and
generate a VALUE out of that (inside the function that
corresponds to the method).

E

···

--
Posted via http://www.ruby-forum.com/\.

4

So, I have a bunch of functions that look like this now:

VALUE get_player_x_pos(VALUE self)
{
  Player* p;
  Data_Get_Struct(self, Player, p);
   rb_float_new(p->position.x);
}

That the way to go?

···

On 12/12/05, Joe Van Dyk <joevandyk@gmail.com> wrote:

On 12/12/05, Joe Van Dyk <joevandyk@gmail.com> wrote:
> (I've already looked at Swig, btw. I'd like to do this one by hand.)
>
> I have the following:
>
> typedef struct {
> double x;
> double y;
> double z;
> } VelocityRecord;
>
> typedef struct {
> double x;
> double y;
> double z;
> } PositionRecord;
>
> typedef struct {
> int id;
> int type;
> PositionRecord position;
> VelocityRecord velocity;
> } Player;
>
> Player Players[10];
>
>
> The number of Players is fixed ahead of time. I want to be able to
> access that data from Ruby. Ideally, something like:
>
> module Simulation
> attr_accessor :players # Other stuff will be here
> class Player
> class VelocityRecord
> attr_accessor :x, :y :z
> end
> class PositionRecord
> attr_accessor :x, :y, :z
> end
> end
> end

Hm, on second thought, it's probably a lot easier to do:

class Player
  attr_reader :x_position, :y_position, :z_position, :x_velocity,
:y_velocity, :z_velocity
end

So, maybe something like this?

void Init_Simulation()
{
  rb_define_module(mSimulation, "Simulation");
  rb_define_class_under(cPlayer, "Player");

  rb_define_method(cPlayer, "x_position", get_x_position, 0);
  rb_define_method(cPlayer, "y_position", get_y_position, 0);
  rb_define_method(cPlayer, "z_position", get_z_position, 0);
  rb_define_method(cPlayer, "x_velocity", get_x_velocity, 0);
  rb_define_method(cPlayer, "y_velocity", get_y_velocity, 0);
  rb_define_method(cPlayer, "z_velocity", get_z_velocity, 0);
}

5

Can you share more details? Is that essentially what I've done in my
later posts on this?

···

On 12/12/05, Eero Saynatkari <ruby-forum-reg@mailinator.com> wrote:

Joe Van Dyk wrote:
> (I've already looked at Swig, btw. I'd like to do this one by hand.)
>
> I have the following:
>
> typedef struct {
> double x;
> double y;
> double z;
> } VelocityRecord;
>
> typedef struct {
> double x;
> double y;
> double z;
> } PositionRecord;
>
> typedef struct {
> int id;
> int type;
> PositionRecord position;
> VelocityRecord velocity;
> } Player;
>
> Player Players[10];
>
>
> The number of Players is fixed ahead of time. I want to be able to
> access that data from Ruby. Ideally, something like:
>
> module Simulation
> attr_accessor :players # Other stuff will be here
> class Player
> class VelocityRecord
> attr_accessor :x, :y :z
> end
> class PositionRecord
> attr_accessor :x, :y, :z
> end
> end
> end

My typical recommendation is to just wrap a pointer to
the struct and pass that around. Then, for each method
just extract the pointer, access the correct field and
generate a VALUE out of that (inside the function that
corresponds to the method).

6

Here's what I have so far. Seems to work well:

#include "ruby.h"
#include "simulation.h"

VALUE get_frame_count(VALUE self) { return INT2NUM(HIFEN2_Count); }
VALUE get_mission_time(VALUE self) { return INT2NUM(HIFEN2_Mission); }
VALUE get_max_players(VALUE self) { return INT2NUM(MAX_PLAYERS); }

VALUE player_new(VALUE self, VALUE rb_i)
{
  int i = NUM2INT(rb_i);
  return Data_Wrap_Struct(self, NULL, NULL, &Players[i]);
}

Player* get_player(VALUE self)
{
  Player *p;
  Data_Get_Struct(self, Player, p);
  return p;
}

VALUE get_player_id(VALUE self) { return INT2NUM(get_player(self)->id); }

VALUE get_player_x_pos(VALUE self) { return
rb_float_new(get_player(self)->position.x); }
VALUE get_player_y_pos(VALUE self) { return
rb_float_new(get_player(self)->position.y); }
VALUE get_player_z_pos(VALUE self) { return
rb_float_new(get_player(self)->position.z); }

VALUE get_player_x_vel(VALUE self) { return
rb_float_new(get_player(self)->velocity.x); }
VALUE get_player_y_vel(VALUE self) { return
rb_float_new(get_player(self)->velocity.y); }
VALUE get_player_z_vel(VALUE self) { return
rb_float_new(get_player(self)->velocity.z); }

VALUE cSimulation;
VALUE cPlayer;

void Init_Sim()
{
  cSimulation = rb_define_class("Simulation", rb_cObject);
  rb_define_method(cSimulation, "frame_count", get_frame_count, 0);
  rb_define_method(cSimulation, "mission_time", get_mission_time, 0);
  rb_define_method(cSimulation, "max_players", get_max_players, 0);

  cPlayer = rb_define_class("Player", rb_cObject);
  rb_define_singleton_method(cPlayer, "new", player_new, 1);
  rb_define_method(cPlayer, "player_id", get_player_id, 0);

  rb_define_method(cPlayer, "x_position", get_player_x_pos, 0);
  rb_define_method(cPlayer, "y_position", get_player_y_pos, 0);
  rb_define_method(cPlayer, "z_position", get_player_z_pos, 0);

  rb_define_method(cPlayer, "x_velocity", get_player_x_vel, 0);
  rb_define_method(cPlayer, "y_velocity", get_player_y_vel, 0);
  rb_define_method(cPlayer, "z_velocity", get_player_z_vel, 0);
}

···

On 12/12/05, Joe Van Dyk <joevandyk@gmail.com> wrote:

On 12/12/05, Eero Saynatkari <ruby-forum-reg@mailinator.com> wrote:
> Joe Van Dyk wrote:
> > (I've already looked at Swig, btw. I'd like to do this one by hand.)
> >
> > I have the following:
> >
> > typedef struct {
> > double x;
> > double y;
> > double z;
> > } VelocityRecord;
> >
> > typedef struct {
> > double x;
> > double y;
> > double z;
> > } PositionRecord;
> >
> > typedef struct {
> > int id;
> > int type;
> > PositionRecord position;
> > VelocityRecord velocity;
> > } Player;
> >
> > Player Players[10];
> >
> >
> > The number of Players is fixed ahead of time. I want to be able to
> > access that data from Ruby. Ideally, something like:
> >
> > module Simulation
> > attr_accessor :players # Other stuff will be here
> > class Player
> > class VelocityRecord
> > attr_accessor :x, :y :z
> > end
> > class PositionRecord
> > attr_accessor :x, :y, :z
> > end
> > end
> > end
>
> My typical recommendation is to just wrap a pointer to
> the struct and pass that around. Then, for each method
> just extract the pointer, access the correct field and
> generate a VALUE out of that (inside the function that
> corresponds to the method).

Can you share more details? Is that essentially what I've done in my
later posts on this?

7

Yep, that looks fine to me. There are certainly other ways but aside
from some repetitiveness, this is easy and versatile (particularly if
you need to pass data to C libraries as well). If you have lots and
lots of functions like that, you could even do with a little #define.

E

···

On 2005.12.13 14:14, Joe Van Dyk <joevandyk@gmail.com> wrote:

On 12/12/05, Joe Van Dyk <joevandyk@gmail.com> wrote:
> On 12/12/05, Eero Saynatkari <ruby-forum-reg@mailinator.com> wrote:
> > Joe Van Dyk wrote:
> > > (I've already looked at Swig, btw. I'd like to do this one by hand.)
> > >
> > > I have the following:
> > >
> > > typedef struct {
> > > double x;
> > > double y;
> > > double z;
> > > } VelocityRecord;
> > >
> > > typedef struct {
> > > double x;
> > > double y;
> > > double z;
> > > } PositionRecord;
> > >
> > > typedef struct {
> > > int id;
> > > int type;
> > > PositionRecord position;
> > > VelocityRecord velocity;
> > > } Player;
> > >
> > > Player Players[10];
> > >
> > >
> > > The number of Players is fixed ahead of time. I want to be able to
> > > access that data from Ruby. Ideally, something like:
> > >
> > > module Simulation
> > > attr_accessor :players # Other stuff will be here
> > > class Player
> > > class VelocityRecord
> > > attr_accessor :x, :y :z
> > > end
> > > class PositionRecord
> > > attr_accessor :x, :y, :z
> > > end
> > > end
> > > end
> >
> > My typical recommendation is to just wrap a pointer to
> > the struct and pass that around. Then, for each method
> > just extract the pointer, access the correct field and
> > generate a VALUE out of that (inside the function that
> > corresponds to the method).
>
> Can you share more details? Is that essentially what I've done in my
> later posts on this?

Here's what I have so far. Seems to work well:

#include "ruby.h"
#include "simulation.h"

VALUE get_frame_count(VALUE self) { return INT2NUM(HIFEN2_Count); }
VALUE get_mission_time(VALUE self) { return INT2NUM(HIFEN2_Mission); }
VALUE get_max_players(VALUE self) { return INT2NUM(MAX_PLAYERS); }

VALUE player_new(VALUE self, VALUE rb_i)
{
  int i = NUM2INT(rb_i);
  return Data_Wrap_Struct(self, NULL, NULL, &Players[i]);
}

Player* get_player(VALUE self)
{
  Player *p;
  Data_Get_Struct(self, Player, p);
  return p;
}

VALUE get_player_id(VALUE self) { return INT2NUM(get_player(self)->id); }

VALUE get_player_x_pos(VALUE self) { return
rb_float_new(get_player(self)->position.x); }
VALUE get_player_y_pos(VALUE self) { return
rb_float_new(get_player(self)->position.y); }
VALUE get_player_z_pos(VALUE self) { return
rb_float_new(get_player(self)->position.z); }

VALUE get_player_x_vel(VALUE self) { return
rb_float_new(get_player(self)->velocity.x); }
VALUE get_player_y_vel(VALUE self) { return
rb_float_new(get_player(self)->velocity.y); }
VALUE get_player_z_vel(VALUE self) { return
rb_float_new(get_player(self)->velocity.z); }

VALUE cSimulation;
VALUE cPlayer;

void Init_Sim()
{
  cSimulation = rb_define_class("Simulation", rb_cObject);
  rb_define_method(cSimulation, "frame_count", get_frame_count, 0);
  rb_define_method(cSimulation, "mission_time", get_mission_time, 0);
  rb_define_method(cSimulation, "max_players", get_max_players, 0);

  cPlayer = rb_define_class("Player", rb_cObject);
  rb_define_singleton_method(cPlayer, "new", player_new, 1);
  rb_define_method(cPlayer, "player_id", get_player_id, 0);

  rb_define_method(cPlayer, "x_position", get_player_x_pos, 0);
  rb_define_method(cPlayer, "y_position", get_player_y_pos, 0);
  rb_define_method(cPlayer, "z_position", get_player_z_pos, 0);

  rb_define_method(cPlayer, "x_velocity", get_player_x_vel, 0);
  rb_define_method(cPlayer, "y_velocity", get_player_y_vel, 0);
  rb_define_method(cPlayer, "z_velocity", get_player_z_vel, 0);
}

8

How does my code differ from what you described?

···

On 12/12/05, Eero Saynatkari <ruby-ml@magical-cat.org> wrote:

On 2005.12.13 14:14, Joe Van Dyk <joevandyk@gmail.com> wrote:
> On 12/12/05, Joe Van Dyk <joevandyk@gmail.com> wrote:
> > On 12/12/05, Eero Saynatkari <ruby-forum-reg@mailinator.com> wrote:
> > > Joe Van Dyk wrote:
> > > > (I've already looked at Swig, btw. I'd like to do this one by hand.)
> > > >
> > > > I have the following:
> > > >
> > > > typedef struct {
> > > > double x;
> > > > double y;
> > > > double z;
> > > > } VelocityRecord;
> > > >
> > > > typedef struct {
> > > > double x;
> > > > double y;
> > > > double z;
> > > > } PositionRecord;
> > > >
> > > > typedef struct {
> > > > int id;
> > > > int type;
> > > > PositionRecord position;
> > > > VelocityRecord velocity;
> > > > } Player;
> > > >
> > > > Player Players[10];
> > > >
> > > >
> > > > The number of Players is fixed ahead of time. I want to be able to
> > > > access that data from Ruby. Ideally, something like:
> > > >
> > > > module Simulation
> > > > attr_accessor :players # Other stuff will be here
> > > > class Player
> > > > class VelocityRecord
> > > > attr_accessor :x, :y :z
> > > > end
> > > > class PositionRecord
> > > > attr_accessor :x, :y, :z
> > > > end
> > > > end
> > > > end
> > >
> > > My typical recommendation is to just wrap a pointer to
> > > the struct and pass that around. Then, for each method
> > > just extract the pointer, access the correct field and
> > > generate a VALUE out of that (inside the function that
> > > corresponds to the method).
> >
> > Can you share more details? Is that essentially what I've done in my
> > later posts on this?
>
> Here's what I have so far. Seems to work well:
>
> #include "ruby.h"
> #include "simulation.h"
>
> VALUE get_frame_count(VALUE self) { return INT2NUM(HIFEN2_Count); }
> VALUE get_mission_time(VALUE self) { return INT2NUM(HIFEN2_Mission); }
> VALUE get_max_players(VALUE self) { return INT2NUM(MAX_PLAYERS); }
>
> VALUE player_new(VALUE self, VALUE rb_i)
> {
> int i = NUM2INT(rb_i);
> return Data_Wrap_Struct(self, NULL, NULL, &Players[i]);
> }
>
> Player* get_player(VALUE self)
> {
> Player *p;
> Data_Get_Struct(self, Player, p);
> return p;
> }
>
> VALUE get_player_id(VALUE self) { return INT2NUM(get_player(self)->id); }
>
> VALUE get_player_x_pos(VALUE self) { return
> rb_float_new(get_player(self)->position.x); }
> VALUE get_player_y_pos(VALUE self) { return
> rb_float_new(get_player(self)->position.y); }
> VALUE get_player_z_pos(VALUE self) { return
> rb_float_new(get_player(self)->position.z); }
>
> VALUE get_player_x_vel(VALUE self) { return
> rb_float_new(get_player(self)->velocity.x); }
> VALUE get_player_y_vel(VALUE self) { return
> rb_float_new(get_player(self)->velocity.y); }
> VALUE get_player_z_vel(VALUE self) { return
> rb_float_new(get_player(self)->velocity.z); }
>
> VALUE cSimulation;
> VALUE cPlayer;
>
> void Init_Sim()
> {
> cSimulation = rb_define_class("Simulation", rb_cObject);
> rb_define_method(cSimulation, "frame_count", get_frame_count, 0);
> rb_define_method(cSimulation, "mission_time", get_mission_time, 0);
> rb_define_method(cSimulation, "max_players", get_max_players, 0);
>
> cPlayer = rb_define_class("Player", rb_cObject);
> rb_define_singleton_method(cPlayer, "new", player_new, 1);
> rb_define_method(cPlayer, "player_id", get_player_id, 0);
>
> rb_define_method(cPlayer, "x_position", get_player_x_pos, 0);
> rb_define_method(cPlayer, "y_position", get_player_y_pos, 0);
> rb_define_method(cPlayer, "z_position", get_player_z_pos, 0);
>
> rb_define_method(cPlayer, "x_velocity", get_player_x_vel, 0);
> rb_define_method(cPlayer, "y_velocity", get_player_y_vel, 0);
> rb_define_method(cPlayer, "z_velocity", get_player_z_vel, 0);
> }

Yep, that looks fine to me. There are certainly other ways but aside
from some repetitiveness, this is easy and versatile (particularly if
you need to pass data to C libraries as well). If you have lots and
lots of functions like that, you could even do with a little #define.

9

CGenerator might be helpful (not used it
myself, but this seems like a prime use case)

martin

···

Eero Saynatkari <ruby-ml@magical-cat.org> wrote:

Yep, that looks fine to me. There are certainly other ways but aside
from some repetitiveness, this is easy and versatile (particularly if
you need to pass data to C libraries as well). If you have lots and
lots of functions like that, you could even do with a little #define.

10

It does not :slight_smile: There are just many ways you could achieve the same
result --of which I consider this the best merely because of the
simplicity.

E

···

On 2005.12.13 16:42, Joe Van Dyk <joevandyk@gmail.com> wrote:

On 12/12/05, Eero Saynatkari <ruby-ml@magical-cat.org> wrote:
> On 2005.12.13 14:14, Joe Van Dyk <joevandyk@gmail.com> wrote:
> > On 12/12/05, Joe Van Dyk <joevandyk@gmail.com> wrote:
> > > On 12/12/05, Eero Saynatkari <ruby-forum-reg@mailinator.com> wrote:
> > > > Joe Van Dyk wrote:
> > > > > (I've already looked at Swig, btw. I'd like to do this one by hand.)
> > > > >
> > > > > I have the following:
> > > > >
> > > > > typedef struct {
> > > > > double x;
> > > > > double y;
> > > > > double z;
> > > > > } VelocityRecord;
> > > > >
> > > > > typedef struct {
> > > > > double x;
> > > > > double y;
> > > > > double z;
> > > > > } PositionRecord;
> > > > >
> > > > > typedef struct {
> > > > > int id;
> > > > > int type;
> > > > > PositionRecord position;
> > > > > VelocityRecord velocity;
> > > > > } Player;
> > > > >
> > > > > Player Players[10];
> > > > >
> > > > >
> > > > > The number of Players is fixed ahead of time. I want to be able to
> > > > > access that data from Ruby. Ideally, something like:
> > > > >
> > > > > module Simulation
> > > > > attr_accessor :players # Other stuff will be here
> > > > > class Player
> > > > > class VelocityRecord
> > > > > attr_accessor :x, :y :z
> > > > > end
> > > > > class PositionRecord
> > > > > attr_accessor :x, :y, :z
> > > > > end
> > > > > end
> > > > > end
> > > >
> > > > My typical recommendation is to just wrap a pointer to
> > > > the struct and pass that around. Then, for each method
> > > > just extract the pointer, access the correct field and
> > > > generate a VALUE out of that (inside the function that
> > > > corresponds to the method).
> > >
> > > Can you share more details? Is that essentially what I've done in my
> > > later posts on this?
> >
> > Here's what I have so far. Seems to work well:
> >
> > #include "ruby.h"
> > #include "simulation.h"
> >
> > VALUE get_frame_count(VALUE self) { return INT2NUM(HIFEN2_Count); }
> > VALUE get_mission_time(VALUE self) { return INT2NUM(HIFEN2_Mission); }
> > VALUE get_max_players(VALUE self) { return INT2NUM(MAX_PLAYERS); }
> >
> > VALUE player_new(VALUE self, VALUE rb_i)
> > {
> > int i = NUM2INT(rb_i);
> > return Data_Wrap_Struct(self, NULL, NULL, &Players[i]);
> > }
> >
> > Player* get_player(VALUE self)
> > {
> > Player *p;
> > Data_Get_Struct(self, Player, p);
> > return p;
> > }
> >
> > VALUE get_player_id(VALUE self) { return INT2NUM(get_player(self)->id); }
> >
> > VALUE get_player_x_pos(VALUE self) { return
> > rb_float_new(get_player(self)->position.x); }
> > VALUE get_player_y_pos(VALUE self) { return
> > rb_float_new(get_player(self)->position.y); }
> > VALUE get_player_z_pos(VALUE self) { return
> > rb_float_new(get_player(self)->position.z); }
> >
> > VALUE get_player_x_vel(VALUE self) { return
> > rb_float_new(get_player(self)->velocity.x); }
> > VALUE get_player_y_vel(VALUE self) { return
> > rb_float_new(get_player(self)->velocity.y); }
> > VALUE get_player_z_vel(VALUE self) { return
> > rb_float_new(get_player(self)->velocity.z); }
> >
> > VALUE cSimulation;
> > VALUE cPlayer;
> >
> > void Init_Sim()
> > {
> > cSimulation = rb_define_class("Simulation", rb_cObject);
> > rb_define_method(cSimulation, "frame_count", get_frame_count, 0);
> > rb_define_method(cSimulation, "mission_time", get_mission_time, 0);
> > rb_define_method(cSimulation, "max_players", get_max_players, 0);
> >
> > cPlayer = rb_define_class("Player", rb_cObject);
> > rb_define_singleton_method(cPlayer, "new", player_new, 1);
> > rb_define_method(cPlayer, "player_id", get_player_id, 0);
> >
> > rb_define_method(cPlayer, "x_position", get_player_x_pos, 0);
> > rb_define_method(cPlayer, "y_position", get_player_y_pos, 0);
> > rb_define_method(cPlayer, "z_position", get_player_z_pos, 0);
> >
> > rb_define_method(cPlayer, "x_velocity", get_player_x_vel, 0);
> > rb_define_method(cPlayer, "y_velocity", get_player_y_vel, 0);
> > rb_define_method(cPlayer, "z_velocity", get_player_z_vel, 0);
> > }
>
> Yep, that looks fine to me. There are certainly other ways but aside
> from some repetitiveness, this is easy and versatile (particularly if
> you need to pass data to C libraries as well). If you have lots and
> lots of functions like that, you could even do with a little #define.

How does my code differ from what you described?

11

Martin DeMello wrote:

Yep, that looks fine to me. There are certainly other ways but aside
from some repetitiveness, this is easy and versatile (particularly if
you need to pass data to C libraries as well). If you have lots and
lots of functions like that, you could even do with a little #define.

CGenerator might be helpful (not used it
myself, but this seems like a prime use case)

martin

I would have mentioned it but the OP wanted to do things the hard way :slight_smile:

Cgen takes care of accessors (including type checking/conversion, marshalling, mark/free when accessors are typed to refer to objects), and also manages inheritance of structure members in parallel with the ruby inheritance hierarchy. It's got a nice wrapper around rb_parse_args. It's also good if you want to dynamically generate the extension in response to loaded code, user input, etc. I've been using it for over 4 years now. The docs need work, though...

An example (simplified from http://redshift.sourceforge.net/cgen/examples/complex.rb.html\):

require 'cgen/cshadow'

class MyComplex < Numeric
   include CShadow
   shadow_attr_accessor :re => "double re", :im => "double im"
end

MyComplex.commit

z = MyComplex.new
z.re = 5
z.im = 1.3
p z

__END__

Output:

#<MyComplex:0x2b04630 im=1.3, re=5.0>

The full example also shows how to add methods written in C (but embedded in your ruby source) to do abs() and in-place multiplication.

Running this example generates a directory with the following contents, which is used to build the extension (all of this happens during the commit call):

C:\ruby\prj\cgen\examples>ls -l MyComplex
total 220
-rw-rw-rw- 1 vjoel 0 45 2005-12-13 09:42 extconf.rb
-rw-rw-rw- 1 vjoel 0 150 2005-12-13 09:42 make.log
-rw-rw-rw- 1 vjoel 0 3619 2005-12-13 09:42 Makefile
-rw-rw-rw- 1 vjoel 0 25 2005-12-13 09:39 MyComplex-i386-mswin32.def
-rwxrwxrwx 1 vjoel 0 3589 2005-12-13 09:39 MyComplex.c
-rw-rw-rw- 1 vjoel 0 589 2005-12-13 09:40 MyComplex.exp
-rw-rw-rw- 1 vjoel 0 762 2005-12-13 09:39 MyComplex.h
-rw-rw-rw- 1 vjoel 0 1976 2005-12-13 09:40 MyComplex.lib
-rw-rw-rw- 1 vjoel 0 17259 2005-12-13 09:39 MyComplex.obj
-rw-rw-rw- 1 vjoel 0 91136 2005-12-13 09:40 MyComplex.pdb
-rw-rw-rw- 1 vjoel 0 20546 2005-12-13 09:40 MyComplex.so
-rw-rw-rw- 1 vjoel 0 53248 2005-12-13 09:39 vc60.pdb

Cgen is careful not to repeat all this work the second time you run the same program--it writes files only if they have changed.

And just to give an idea of what functions it handles:

C:\ruby\prj\cgen\examples\MyComplex>grep "^\w" MyComplex.c
static void mark_MyComplex_Shadow(MyComplex_Shadow *shadow);
static void free_MyComplex_Shadow(MyComplex_Shadow *shadow);
VALUE module_MyComplex;
void Init_MyComplex(void)
static void mark_MyComplex_Shadow(MyComplex_Shadow *shadow)
static void free_MyComplex_Shadow(MyComplex_Shadow *shadow)
VALUE __dump__data_module_MyComplex_method(VALUE self)
VALUE __load__data_module_MyComplex_method(VALUE self, VALUE from_array)
VALUE im_module_MyComplex_method(VALUE self)
VALUE im_equals_module_MyComplex_method(int argc, VALUE *argv, VALUE self)
VALUE re_module_MyComplex_method(VALUE self)
VALUE re_equals_module_MyComplex_method(int argc, VALUE *argv, VALUE self)
VALUE new_module_MyComplex_singleton_method(int argc, VALUE *argv, VALUE self)
VALUE alloc_func_module_MyComplex(VALUE klass)

Here's an example (sample.rb) showing the argument parsing wrapper:

lib2.define_c_singleton_method(Point, :test).instance_eval {
   c_array_args {
     required :arg0, :arg1
     optional :arg2, :arg3, :arg4
     typecheck :arg2 => Numeric, :arg3 => Numeric
     default :arg3 => "INT2NUM(7)",
               :arg4 => "INT2NUM(NUM2INT(arg2) + NUM2INT(arg3))"
     rest :rest
     block :block
   }
   body %{\
     rb_funcall(block, #{declare_symbol :call}, 6,
                arg0, arg1, arg2, arg3, arg4, rest);
   }
}

···

Eero Saynatkari <ruby-ml@magical-cat.org> wrote:

--
        vjoel : Joel VanderWerf : path berkeley edu : 510 665 3407