From: ptkwt@... (Phil Tomson)
Date: 2005-08-04T02:06:07+09:00
Subject: Re: symbols in C extensions

In article <7993c66305080305224adfe2ce@mail.gmail.com>,
Brian Schr�der  <ruby.brian@gmail.com> wrote:
>On 03/08/05, Paolo Capriotti <p.capriotti@gmail.com> wrote:
>> Is there a better (i.e. faster) way to create a symbol in a C
>> extension than writing: rb_eval_string(":my_symbol")?
>>=20
>> Thanks,
>>=20
>> Paolo.
>>=20
>>=20
>
>From README.EXT:
>
> :Identifier
>
>You can get the symbol value from a string within C code by using
>
>  rb_intern(const char *name)
>
>regards,
>
>Brian
>
>
>--=20
>http://ruby.brian-schroeder.de/
>
>Stringed instrument chords: http://chordlist.brian-schroeder.de/
>
>

Also, to speed things up in cases where you'll need to use the same 
symbols over and over you can do the rb_intern in the Init function of 
your extension, for example:

  #include "ruby.h"
  #include <math.h>
  #include <stdio.h>

  static int id_x;
  static int id_y;
  static int id_equal;


.... a lot of snippage ...

  VALUE cACOMod;
  VALUE cACOPoint;
  VALUE cACOGraph;


 void Init_ACO_Ext() {
   printf("ACO_Ext initializing...\n");
   cACOMod = rb_define_module("ACO");
   cACOPoint = rb_define_class_under(cACOMod,"Point",rb_cObject);
   cACOGraph = rb_define_class_under(cACOMod,"Graph",rb_cObject);
   rb_define_alloc_func(cACOPoint, aco_point_alloc);
   rb_define_method(cACOPoint,"initialize",aco_point_init,2);
   rb_define_method(cACOPoint,"-",aco_point_diff,1);
   rb_define_method(cACOPoint,"==",aco_point_equal,1);
   rb_define_method(cACOPoint,"x",aco_point_getx,0);
   rb_define_method(cACOPoint,"y",aco_point_gety,0);

   //create your symbols ahead of time here:
   id_x      = rb_intern("x");
   id_y      = rb_intern("y");
   id_equal  = rb_intern("==");
 }



Seems like it could help save some time if you use the symbols lots of 
times in your accessor functions for example.

Phil