Help with a Windows port of a Ruby extension

[Scott Mckie]

I'm working on a game that's in the early stages, and I want to make
sure it runs on both OS X and Windows before I continue development. OS
X is my primary OS, and it runs fine on that. But it crashes in
Windows.

The setup is this: the core of the game is written in Objective C, and
I'm using Ruby for the scripting of the game. I wrote a very small Ruby
extension to act as a bridge between the two (basically a wrapper around
the Objective C game objects). Everything was fine, in OS X. In order
to get it to compile in Windows, I had to write a separate extension to
act as a wrapper around the Objective C /classes/ and do a hairy little
dance to register them, because I don't of a compiler flag in the
standard gcc that's an equivalent of Apple's -undefined suppress, and I
don't want to link against all the main project files in the extension.

And so, my current problem: it still runs fine in OS X, but it chokes
when I try to create the Objective C object from within the Ruby
extension. I create the Ruby class-wrapper object, register the
Objective C class, test it thoroughly to make sure that it's behaving as
expected -- it's all fine when I do it from the main program. I even
tried printing the pointer to the Obj-C class to make sure it's not
getting mangled, and it doesn't seem to change at all. But all I get is
garbage when I try to instantiate the class.

I realize that my problem might likely turn out to have nothing to do
with Ruby itself. In truth, the Ruby part seems to be behaving as
expected. I pose the question here because I think I'm likely to find
more Ruby people with experience in Objective C than Objective C people
with experience in Ruby. And likewise for Windows.

I'm using Ruby 1.8.6 on both machines. My Mac is running OS 10.4.10,
and the Windows machine I'm using for development is ... Windows XP
Home. I'll put the source up at
http://greay.phpwebhosting.com/shooter/shooter.r67.zip for people to
look at, as well.

 

[John Joyce]

I'm working on a game that's in the early stages, and I want to make
sure it runs on both OS X and Windows before I continue
development. OS
X is my primary OS, and it runs fine on that. But it crashes in
Windows.

The setup is this: the core of the game is written in Objective C,
and
I'm using Ruby for the scripting of the game. I wrote a very small
Ruby
extension to act as a bridge between the two (basically a wrapper
around
the Objective C game objects). Everything was fine, in OS X. In
order
to get it to compile in Windows, I had to write a separate
extension to
act as a wrapper around the Objective C /classes/ and do a hairy
little
dance to register them, because I don't of a compiler flag in the
standard gcc that's an equivalent of Apple's -undefined suppress,
and I
don't want to link against all the main project files in the
extension.

And so, my current problem: it still runs fine in OS X, but it chokes
when I try to create the Objective C object from within the Ruby
extension. I create the Ruby class-wrapper object, register the
Objective C class, test it thoroughly to make sure that it's
behaving as
expected -- it's all fine when I do it from the main program. I even
tried printing the pointer to the Obj-C class to make sure it's not
getting mangled, and it doesn't seem to change at all. But all I
get is
garbage when I try to instantiate the class.

I realize that my problem might likely turn out to have nothing to do
with Ruby itself. In truth, the Ruby part seems to be behaving as
expected. I pose the question here because I think I'm likely to find
more Ruby people with experience in Objective C than Objective C
people
with experience in Ruby. And likewise for Windows.

I'm using Ruby 1.8.6 on both machines. My Mac is running OS 10.4.10,
and the Windows machine I'm using for development is ... Windows XP
Home. I'll put the source up at
http://greay.phpwebhosting.com/shooter/shooter.r67.zip for people to
look at, as well.

Well, if you want Objective-C to be portable, you'll have to build it
with GNUStep/OpenStep instead of Cocoa.
This can be difficult since many functions and libraries in Cocoa are
not found in the GNU stuff.
For the most part you can consider Objective-C to be OS X only, just
as much of what is written for Windows uses Windows-only code that
can't be ported, or ported easily.
Regardless, Windows doesn't include the necessary runtime for
Objective-C.
You might want to re-write using another language instead of Obj-C to
make it crossplatform.

 

[Scott Mckie]

Well, if you want Objective-C to be portable, you'll have to build it
with GNUStep/OpenStep instead of Cocoa.
This can be difficult since many functions and libraries in Cocoa are
not found in the GNU stuff.

Cocoa might not be portable, but Objective C most certainly is. I've
gotten Objective C code running on the Dreamcast.

I don't use Cocoa in this project. I'm using the Objective C runtime
that comes with gcc and pretty much only use the base Object class. All
my classes inherit from that. An earlier version of the game (before I
wrote the Ruby extension) worked on Windows, and that was all in
Objective C. So I don't think that's the problem.

 

[John Joyce]

Cocoa might not be portable, but Objective C most certainly is. I've
gotten Objective C code running on the Dreamcast.

I don't use Cocoa in this project. I'm using the Objective C runtime
that comes with gcc and pretty much only use the base Object
class. All
my classes inherit from that. An earlier version of the game
(before I
wrote the Ruby extension) worked on Windows, and that was all in
Objective C. So I don't think that's the problem.

Well, sorry for the noise then.
Not real familiar with Cygwin.
Does it allow you to use *nix style paths instead of windows style
paths? Or is that even still an issue?
I noticed you used DarwinPorts/MacPorts (whatever they're calling it
now)
is it possibly some kind of path/dependency trouble? Maybe it's
expecting to see something at a path that isn't what it expects?
It's interesting...

 

[Scott Mckie]

is it possibly some kind of path/dependency trouble? Maybe it's
expecting to see something at a path that isn't what it expects?
It's interesting...

The paths aren't the issue. Cygwin lets you use *NIX style paths, yes.
But the game loads both Ruby extensions without hitch, and I'm able to
instantiate at least one of them w/o problem. It's when I try to access
the C Data structure from /within/ the Ruby extension that I run into
problems. The confusing thing is I can still access the C Data structure
from the main program, and it will behave as expected.

I'd thought that the problem might be some weird memory protection thing
peculiar to Windows that was preventing me from accessing the class
methods (virtual memory pages or some such junk), but I've done some
more testing and /that/ doesn't seem to be the case, thank god. So my
last two ideas are that there are some compiler/linker flags that are
causing the problem, or some weird differences between Apple's and GNU's
Objective C runtimes.

Very, very frustrating.

 

[John Joyce]

The paths aren't the issue. Cygwin lets you use *NIX style paths,
yes.
But the game loads both Ruby extensions without hitch, and I'm able to
instantiate at least one of them w/o problem. It's when I try to
access
the C Data structure from /within/ the Ruby extension that I run into
problems. The confusing thing is I can still access the C Data
structure
from the main program, and it will behave as expected.

I'd thought that the problem might be some weird memory protection
thing
peculiar to Windows that was preventing me from accessing the class
methods (virtual memory pages or some such junk), but I've done some
more testing and /that/ doesn't seem to be the case, thank god. So my
last two ideas are that there are some compiler/linker flags that are
causing the problem, or some weird differences between Apple's and
GNU's
Objective C runtimes.

Very, very frustrating.

Well, good luck! That sounds like uncharted waters.
Maybe you'll have to backtrack a bit and simplify the Ruby. See what
it will respond to.