From: Charles Mills <cmills@...>
Date: 2004-07-24T01:14:17+09:00
Subject: mkmf.rb

Just wondering if there is a system as to which global variables are 
Arrays and which are Strings.
For example $objs and $defs are Arrays and $LOCAL_LIBS, $libs and $LIBS 
are all Strings.
I end up redefining $LOCAL_LIBS as an Array so I can do things like:
def local_lib_rules()
   str = "\n"
   $LOCAL_LIBS.each do |lib|
     dir = File.dirname(lib)
     str << lib << ":\n"
     str << "\tcd #{dir} && $(MAKE)\n"
   end
   str << "\n"
end
# ....
# but then have to
$LOCAL_LIBS = $LOCAL_LIBS.join(' ')
# later in my code.

Also I have been using this function to determine the byte order, 
perhaps it would be useful to somebody.
def check_byte_order(headers = nil, opt = "", &b)
   message "checking byte order... "
   src = %{#{COMMON_HEADERS}
#{headers}
#include <stdio.h>
/*top*/
int
main(void)
{
   long a = 1;
   if (*(char*)&a == 1)
     printf("1234\\n");
   else
     printf("4321\\n");
   return 0;
}
}
   order = nil
   if try_link0(src, opt, &b)
     xpopen("./conftest") do |f|
       order = f.gets
     end
     message "#{order}"
   else
     message "error\n"
     exit 1
   end
   order
end

-Charlie