Tcl模块：找不到架构x86_64的符号

Question

我正在从Swig教程网站http://www.swig.org/tutorial.html运行测试tcl模块。

但是，当我在命令行中输入：gcc -shared example.o example_wrap.o -o example.so时，它会返回：

Undefined symbols for architecture x86_64:
  "_TclFreeObj", referenced from:
      __wrap_My_variable_get in example_wrap.o
      __wrap_My_variable_set in example_wrap.o
    .
    . 
    .

ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)

有关问题的任何建议？