From: Lui Core <usurffx@...>
Date: 2009-08-14T01:07:27+09:00
Subject: One Way to Write VCRuntime-Independent Extensions on Windows

Solve (rather stupid):
Don't use ruby's includes and libs. Use Win32 API
GetProcAddress(hmodule, strFunction) to locate ruby's C-APIs.

The following is a simple experiment with VC2008 Express and
ruby191-mswin32_90 and ruby191-mingw32:

[ho.c]
--------------------------------------------------------
#include <stdio.h>
#include <windows.h>

void Init_ho() {
    HMODULE h = 0;
    FARPROC p = 0;

    // why they create so many dll names ...?
    if(!h) h = GetModuleHandle("msvcrt-ruby191.dll");
    if(!h) h = GetModuleHandle("msvcrt60-ruby191.dll");
    if(!h) h = GetModuleHandle("msvcrt70-ruby191.dll");
    if(!h) h = GetModuleHandle("msvcrt80-ruby191.dll");
    if(!h) h = GetModuleHandle("msvcrt90-ruby191.dll");
    if(!h) h = GetModuleHandle("msvcrt100-ruby191.dll");
    // and many others ...

    if(!h) {
        printf("failed");
        return;
    }

    p = GetProcAddress(h, "rb_io_check_readable");
    // and may others ...

    /* if imported functions are the same in ruby1.8 and ruby1.9,
       then a cross-version extension ? */

    if(p) {
        printf("loaded\n");
    }
}
--------------------------------------------------------

[ho.def]
--------------------------------------------------------
EXPORTS
Init_ho
--------------------------------------------------------

building commands are (not using extconf.rb)
  cl -c ho.c
  cl -LD -MD -Feho.so ho.obj user32.lib -link -def:ho.def

some explanations of the commands:
-LD : link dll
-MD : statically link
-Fe : output file name
-link -def:ho.def : make entry point Init_ho searchable for ruby

require 'ho.so' will simply print "loaded" on console.
Both ruby191-mswin32_90 and ruby191-mingw32 can load it properly.
-- 
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