From: gw <gw@...>
Date: 2005-01-04T03:50:00+09:00
Subject: Re: wrapping Ruby around OLD code

E S <eero.saynatkari@kolumbus.fi> Wrote:

>> L�hett�j�: gw <gw@citasystems.com>
>> 5 years ago one of our smart guys suggested we throw away our home grown 
"Basic" which glues our 
[SNIP]
>
>As long as the main manipulation of the data structures
>happens in C, the following would apply:
>
>Instead of actually mapping the datatypes to Ruby, you can simply
>wrap them inside opaque Ruby objects and pass them around that way.
>Say you've defined a Ruby class 'MyData' (which in Ruby C is a
>variable, traditionally c_MyData):
>
>// You'd normally call this in your C code
>extern void do_something(struct whatever * ptr);
>
>#include 'ruby.h'
>
>// VALUE is the basic Ruby type in C
>VALUE make_opaque_wrapper(struct whatever * ptr) {
>  // See 'Programming Ruby'
>  VALUE wrapper = Data_Wrap_Struct(c_MyData, 0, 0, ptr);
>  return wrapper;
>}
> 
>// Wrapper function to access the normal C functions again
>void access_do_something(VALUE wrapper) {
>  // Extract the C structure
>  struct whatever * ptr = 0;
>  Data_Get_Struct(wrapper, struct whatever, ptr);
>  // Call the C function
>  do_something(ptr);
>  return;
>}
>
>And so on. You'll want to read the links to Programming Ruby
>given earlier. 
>
>This way your Ruby interface can be pretty much anything you
>need. If you need to use values from those data structures *in*
>Ruby (for manipulation or whatever), you can just write extraction
>functions to be called at those times.
>
>E
>
>
Execellent advice, sir. Thank you for your considerate answer.

George Wyche