From: Aaron Patterson <aaron@...>
Date: 2009-08-14T01:52:52+09:00
Subject: Re: Ruby/DL question

On Thu, Aug 13, 2009 at 07:06:51PM +0900, Gin Mendi wrote:
> Been trying to learn how to use ruby and Ruby/DL and I'm unsure how to
> implement this:
> 
> I have a callback function in C which I want to implement in ruby
> 
> void my_callback(my_struct resultList, DWORD count)
> {
>   while (count != 0)
>   {
>     if (resultList != NULL)
>     {
>       printf("field1 - %s , field2 - %f \n", resultList->field1,
> resultList->field2);
>     }
>     resultList++;
>     count--;
>   }
> }
> 
> I started with this:
> 
> MY_CALLBACK = DL.callback('0PL') { |result_list, count|
>   if result_list
>     record = MyStruct.new(result_list)
>     puts record.field1
>   end
> }
> 
> My problem is I don't know how to get the other records if result_list
> points to 2 or more records. I want to be able to traverse the whole set
> or records like in the C callback function. I understand that I will
> need to loop "count" times but how do I make my pointer point to the
> next record?

Result list should always be a pointer to a pointer, right?  If that is
the case, you need to create a struct of size count that contains that array.

From the new list struct, you should be able to access each MyStruct.

-- 
Aaron Patterson
http://tenderlovemaking.com/