在Mac OS X上使用SWIG为Ruby编译库

Question

我尝试编译下面的库，直到最后一步，一切都很顺利。

/* File : computation.c */
int add(int x, int y) {
  return x + y;
}

/* File: computation.i */
%module computation
extern int add(int x, int y);

$ swig -ruby computation.i
$ gcc -c computation.c
$ gcc -c computation_wrap.c -I/opt/local/lib/ruby/1.8/i686-darwin10
$ gcc -shared computation.o computation_wrap.o -o computation.so

Undefined symbols:
  "_rb_str_cat", referenced from:
      _Ruby_Format_TypeError in computation_wrap.o
  "_rb_exc_new3", referenced from:
      _SWIG_Ruby_ExceptionType in computation_wrap.o
  "_rb_define_class_under", referenced from:
      _SWIG_Ruby_define_class in computation_wrap.o
      _SWIG_Ruby_define_class in computation_wrap.o
[...]
ld: symbol(s) not found
collect2: ld returned 1 exit status

我的配置：

$ sw_vers
ProductName:  Mac OS X
ProductVersion: 10.6.3
BuildVersion: 10D575
$ ruby -v
ruby 1.8.7 (2010-01-10 patchlevel 249) [i686-darwin10]
$ swig -version
SWIG Version 1.3.40
Compiled with /usr/bin/g++-4.2 [i386-apple-darwin10.3.0]
$ gcc --version
i686-apple-darwin10-gcc-4.2.1 (GCC) 4.2.1 (Apple Inc. build 5646)

Answer 1

尝试使用以下标志编译共享对象：

$ gcc -bundle -flat_namespace -undefined suppress computation.o computation_wrap.o -o computation.so

您可能还需要添加“Ruby”，因为看起来您在雪豹上运行的是32位-arch i386。