• Jordan Miner (10/10) Jan 16 2009 Hello,
• Denis Koroskin (3/29) Jan 16 2009 Try the following:
• Jordan Miner (2/6) Jan 17 2009 I forgot to mention it, but I already have extern(C): at the beginning o...
• torhu (3/6) Jan 17 2009 For accessing variables in a DLL, you need to do it like this:
• Jordan Miner (2/13) Jan 17 2009 That worked, thank you! I already had extern(C): at the top of the file,...

Jordan Miner <TheUndaunted NOSPAM.gmail.com> writes:

Hello,

I recently wrote a binding to Ruby’s extension API , and today finished writing
a simple extension using it. But I ran into something strange. (I also had a
problem compiling the DLL since I use Tango, but searching the newsgroup
yielded the solution.)

Ruby’s API has rb_cObject, rb_cString, etc. as global variables that it sets to
the Object class, String class etc. In ruby.h, they are defined as

extern unsigned long rb_cObject;

so in my binding I have

extern uint rb_cObject;

But when I try to use rb_cObject from my extension, it is not the right
value... I think rb_cObject should equal rb_eval_string("Object"), but it does
not. (Using the wrong value causes an access violation.)

I produced an OMF import library for Ruby’s runtime DLL by using coff2omf on
the COFF import library that ships with it. I'm linking my extension with this
import library.

If I remove the extern from my binding, I get a multiple definition error, so I
must be linking with the variable in the DLL? But it seems the value is wrong.
I’ve worked around this by calling rb_eval_string("Object") instead, but I’m
really curious what could be happening here. Using rb_cObject is the usual way
of referring to the Object class in C extensions, and I want to make sure my
binding is correct. Could it be because the DLL was compiled with Visual Studio
and my extension is in D?

Any ideas?

"Denis Koroskin" <2korden gmail.com> writes:

On Sat, 17 Jan 2009 06:30:35 +0300, Jordan Miner
<TheUndaunted nospam.gmail.com> wrote:

 Hello,

 I recently wrote a binding to Ruby’s extension API , and today finished  
 writing a simple extension using it. But I ran into something strange.  
 (I also had a problem compiling the DLL since I use Tango, but searching  
 the newsgroup yielded the solution.)

 Ruby’s API has rb_cObject, rb_cString, etc. as global variables that it  
 sets to the Object class, String class etc. In ruby.h, they are defined  
 as

 extern unsigned long rb_cObject;

 so in my binding I have

 extern uint rb_cObject;

 But when I try to use rb_cObject from my extension, it is not the right  
 value... I think rb_cObject should equal rb_eval_string("Object"), but  
 it does not. (Using the wrong value causes an access violation.)

 I produced an OMF import library for Ruby’s runtime DLL by using  
 coff2omf on the COFF import library that ships with it. I'm linking my  
 extension with this import library.

 If I remove the extern from my binding, I get a multiple definition  
 error, so I must be linking with the variable in the DLL? But it seems  
 the value is wrong. I’ve worked around this by calling  
 rb_eval_string("Object") instead, but I’m really curious what could be  
 happening here. Using rb_cObject is the usual way of referring to the  
 Object class in C extensions, and I want to make sure my binding is  
 correct. Could it be because the DLL was compiled with Visual Studio and  
 my extension is in D?

 Any ideas?

Try the following:

extern(C) extern uint rb_cObject;

Jordan Miner <TheUndaunted NOSPAM.gmail.com> writes:

Denis Koroskin Wrote:

 Try the following:
 
 extern(C) extern uint rb_cObject;
 

I forgot to mention it, but I already have extern(C): at the beginning of the
file.

torhu <no spam.invalid> writes:

On 17.01.2009 04:30, Jordan Miner wrote:
 extern unsigned long rb_cObject;

 so in my binding I have

 extern uint rb_cObject;

For accessing variables in a DLL, you need to do it like this:

export extern (C) extern uint rb_cObject;

Jordan Miner <TheUndaunted NOSPAM.gmail.com> writes:

torhu Wrote:

 On 17.01.2009 04:30, Jordan Miner wrote:
 extern unsigned long rb_cObject;

 so in my binding I have

 extern uint rb_cObject;

 
 For accessing variables in a DLL, you need to do it like this:
 
 export extern (C) extern uint rb_cObject;
 

That worked, thank you! I already had extern(C): at the top of the file, but I
hadn't thought of adding export.