From: Saumya Garg <skg1@...>
Date: 2004-08-19T05:35:56+09:00
Subject: Module Extension problem

I am trying to write a Module written in C for ruby to help me do some 
image processing.

I get the following error when I try to run my code.


processImg.rb:7:in `OpenFile': cannot convert Module into String (TypeError)
         from /home/usr/johnDoe/processImg.rb:7


Below is a simplified example of my code that generates the same error.

C code:

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

static VALUE getFile(VALUE nameFile){
   char *fileName = STR2CSTR(nameFile);
   FILE *pFile;
   long lSize;
   float *buffer;
   pFile = fopen (fileName, "rb" );
   // obtain file size.
   fseek (pFile , 0 , SEEK_END);
   lSize = ftell (pFile);
   rewind (pFile);
   buffer = (float*) malloc (lSize);
   // copy the file into the buffer.
   fread (buffer,1,lSize,pFile);
   fclose (pFile);
   VALUE data =  Data_Make_Struct(data,float,0,free, buffer);
   return data;
}

static VALUE writeFile(VALUE data, VALUE nameFile){
   float *img;
   Data_Get_Struct(data, float, img);
   char *fileName = STR2CSTR(nameFile);
   FILE * pFile;
   int sizeFloat = sizeof(float);
   int numberFloats = sizeof(*img) / sizeFloat;
   pFile = fopen (fileName , "w");
   fwrite (img, sizeFloat,numberFloats, pFile);
   fclose (pFile);
   free (img);
   return Qnil;
}

static VALUE cImageFile;

void Init_Image_File(){
   cImageFile = rb_define_module("Image_File");
   rb_define_module_function(cImageFile,"OpenFile",getFile,1);
   rb_define_module_function(cImageFile,"WriteFile",writeFile,2);
   rb_define_module_function(cImageFile,"FreeMem",freeMem, 1);
}


Ruby Code:

require 'Image_File'

imageName = ARGV[0]
newImageName = ARGV[1]
puts (imageName)

data = Image_File.OpenFile(imageName)
Image_File.WriteFile(data, newImageName)



Thanks in advance for your help.