_main 在来自 cython 的 link 期间未定义

Question

我正在尝试从最小的 Python 文件生成二进制文件：

print 'hello'

使用此生成文件：

#!/usr/bin/make -f

export

flags=
cflags=$(flags) $(shell python-config --cflags)
ldflags=$(flags) $(shell python-config --ldflags)

all: multi

.PRECIOUS: %.o %.c

multi: multi.o makefile
    gcc -o $@ $< $$ldflags

%.o: %.c makefile
    gcc -o $@ $< $$cflags -c

%.c: %.py makefile
    cython $<

没什么特别的...但我得到：

$ make
cython multi.py
gcc -o multi.o multi.c $cflags -c
multi.c:1318:28: warning: unused function '__Pyx_PyObject_AsString' [-Wunused-function]
static CYTHON_INLINE char* __Pyx_PyObject_AsString(PyObject* o) {
                           ^
multi.c:1315:32: warning: unused function '__Pyx_PyUnicode_FromString' [-Wunused-function]
static CYTHON_INLINE PyObject* __Pyx_PyUnicode_FromString(const char* c_str) {
                               ^
multi.c:308:29: warning: unused function '__Pyx_Py_UNICODE_strlen' [-Wunused-function]
static CYTHON_INLINE size_t __Pyx_Py_UNICODE_strlen(const Py_UNICODE *u)
                            ^
multi.c:1380:26: warning: unused function '__Pyx_PyObject_IsTrue' [-Wunused-function]
static CYTHON_INLINE int __Pyx_PyObject_IsTrue(PyObject* x) {
                         ^
multi.c:1430:33: warning: unused function '__Pyx_PyIndex_AsSsize_t' [-Wunused-function]
static CYTHON_INLINE Py_ssize_t __Pyx_PyIndex_AsSsize_t(PyObject* b) {
                                ^
multi.c:1455:33: warning: unused function '__Pyx_PyInt_FromSize_t' [-Wunused-function]
static CYTHON_INLINE PyObject * __Pyx_PyInt_FromSize_t(size_t ival) {
                                ^
multi.c:1033:32: warning: unused function '__Pyx_PyInt_From_long' [-Wunused-function]
static CYTHON_INLINE PyObject* __Pyx_PyInt_From_long(long value) {
                               ^
multi.c:1080:27: warning: function '__Pyx_PyInt_As_long' is not needed and will not be emitted [-Wunneeded-internal-declaration]
static CYTHON_INLINE long __Pyx_PyInt_As_long(PyObject *x) {
                          ^
multi.c:1175:26: warning: function '__Pyx_PyInt_As_int' is not needed and will not be emitted [-Wunneeded-internal-declaration]
static CYTHON_INLINE int __Pyx_PyInt_As_int(PyObject *x) {
                         ^
9 warnings generated.
multi.c:1318:28: warning: unused function '__Pyx_PyObject_AsString' [-Wunused-function]
static CYTHON_INLINE char* __Pyx_PyObject_AsString(PyObject* o) {
                           ^
multi.c:1315:32: warning: unused function '__Pyx_PyUnicode_FromString' [-Wunused-function]
static CYTHON_INLINE PyObject* __Pyx_PyUnicode_FromString(const char* c_str) {
                               ^
multi.c:308:29: warning: unused function '__Pyx_Py_UNICODE_strlen' [-Wunused-function]
static CYTHON_INLINE size_t __Pyx_Py_UNICODE_strlen(const Py_UNICODE *u)
                            ^
multi.c:1380:26: warning: unused function '__Pyx_PyObject_IsTrue' [-Wunused-function]
static CYTHON_INLINE int __Pyx_PyObject_IsTrue(PyObject* x) {
                         ^
multi.c:1430:33: warning: unused function '__Pyx_PyIndex_AsSsize_t' [-Wunused-function]
static CYTHON_INLINE Py_ssize_t __Pyx_PyIndex_AsSsize_t(PyObject* b) {
                                ^
multi.c:1455:33: warning: unused function '__Pyx_PyInt_FromSize_t' [-Wunused-function]
static CYTHON_INLINE PyObject * __Pyx_PyInt_FromSize_t(size_t ival) {
                                ^
multi.c:1033:32: warning: unused function '__Pyx_PyInt_From_long' [-Wunused-function]
static CYTHON_INLINE PyObject* __Pyx_PyInt_From_long(long value) {
                               ^
multi.c:1080:27: warning: function '__Pyx_PyInt_As_long' is not needed and will not be emitted [-Wunneeded-internal-declaration]
static CYTHON_INLINE long __Pyx_PyInt_As_long(PyObject *x) {
                          ^
multi.c:1175:26: warning: function '__Pyx_PyInt_As_int' is not needed and will not be emitted [-Wunneeded-internal-declaration]
static CYTHON_INLINE int __Pyx_PyInt_As_int(PyObject *x) {
                         ^
9 warnings generated.
gcc -o multi multi.o $ldflags
Undefined symbols for architecture x86_64:
  "_main", referenced from:
     implicit entry/start for main executable
     (maybe you meant: ___pyx_module_is_main_multi)
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
make: *** [multi] Error 1

Answer 1

您正在尝试构建一个可执行文件，其中 cython 旨在创建 python 扩展。因此将使用 Python 解释器的 main。

文档明确指出您使用不带 distutils 的 cython 的方法是为了调试目的。请改用 distutils，如教程中所述，然后导入您的模块以执行代码。

或者，link 您的目标文件 Python DLL/so，并自己添加一个主函数。

_main 在来自 cython 的 link 期间未定义

_main undefined during link from cython

python

python-2.7

cython