如何在Cython中使用atexit？

Question

我试图在cython中编译以下代码

from cython_gsl cimport *

import atexit

cdef gsl_rng_type * rng_T = gsl_rng_default
cdef gsl_rng * rng_r

gsl_rng_env_setup()
rng_r = gsl_rng_alloc(rng_T)

@atexit.register
def free_gsl_rng():
    gsl_rng_free(rng_r)

但我总是得到错误

分配给非左值'atexit'

对应的.pxd文件

from cython_gsl cimport *

cdef gsl_rng * rng_r

---

我实际上是用SageMath 8.7编译的

sage setup.py build_ext --inplace

这是我的setup.py

from distutils.core import setup
from distutils.extension import Extension
from Cython.Distutils import build_ext
from Cython.Build import cythonize
import cython_gsl

extensions = [
        Extension("gsl_rand", ["gsl_rand.pyx"],
            libraries=cython_gsl.get_libraries(),
            library_dirs=[cython_gsl.get_library_dir()],
            include_dirs=[cython_gsl.get_cython_include_dir()]
            ),
        ]

setup(
        name='Simulation of k-cut on conditional Galton-Watson trees',
        cmdclass={'build_ext': build_ext},
        include_dirs = [cython_gsl.get_include()],
        ext_modules=cythonize(extensions),
        )

---

Full error log here

sage setup.py build_ext --inplace
Compiling gsl_rand.pyx because it changed.
[1/1] Cythonizing gsl_rand.pyx
/home/xing/Downloads/software/sage/8.7/local/lib/python2.7/site-packages/Cython/Compiler/Main.py:367: FutureWarning: Cython directive 'language_level' not set, using 2 for now (Py2). This will change in a later release! File: /home/xing/Dropbox/Research/2017/k-cut/GW/sage/moments/cython-v5/gsl_rand.pxd
  tree = Parsing.p_module(s, pxd, full_module_name)
warning: /home/xing/Downloads/software/sage/8.7/local/lib/python2.7/site-packages/cython_gsl/gsl_integration.pxd:65:9: 'GSL_EMAXITER' redeclared 
warning: /home/xing/Downloads/software/sage/8.7/local/lib/python2.7/site-packages/cython_gsl/gsl_integration.pxd:67:9: 'GSL_EROUND' redeclared 
warning: /home/xing/Downloads/software/sage/8.7/local/lib/python2.7/site-packages/cython_gsl/gsl_integration.pxd:69:9: 'GSL_ESING' redeclared 
warning: /home/xing/Downloads/software/sage/8.7/local/lib/python2.7/site-packages/cython_gsl/gsl_integration.pxd:71:9: 'GSL_EDIVERGE' redeclared 
warning: gsl_rand.pyx:14:0: Overriding cdef method with def method.

Error compiling Cython file:
------------------------------------------------------------
...
# cython: profile=False

from cython_gsl cimport *

import atexit
      ^
------------------------------------------------------------

gsl_rand.pyx:5:7: Assignment to non-lvalue 'atexit'

Error compiling Cython file:
------------------------------------------------------------
...
cdef gsl_rng * rng_r

gsl_rng_env_setup()
rng_r = gsl_rng_alloc(rng_T)

@atexit.register
^
------------------------------------------------------------

gsl_rand.pyx:13:0: Object of type 'int (void (*)(void) nogil) nogil' has no attribute 'register'
Traceback (most recent call last):
  File "setup.py", line 29, in <module>
    ext_modules=cythonize(extensions),
  File "/home/xing/Downloads/software/sage/8.7/local/lib/python2.7/site-packages/Cython/Build/Dependencies.py", line 1097, in cythonize
    cythonize_one(*args)
  File "/home/xing/Downloads/software/sage/8.7/local/lib/python2.7/site-packages/Cython/Build/Dependencies.py", line 1220, in cythonize_one
    raise CompileError(None, pyx_file)
Cython.Compiler.Errors.CompileError: gsl_rand.pyx

Answer 1

atexit正在加入from cython_gsl cimport *。这似乎发生在from libc.stdlib cimport *线上。因此，此名称与Python atexit模块冲突。我认为这是一个很好的例子，为什么不推荐使用from something [c]import *，无论是在代码中还是在cython_gsl的代码中。它变得有点混乱，因为Cython有两种类型的名称（对于Python和C），所以你得到奇怪的错误消息。

最好的解决方案是做cimport cython_gsl或cimport你需要的特定符号：from cython_gsl cimport gsl_rng, etc。请记住更改pyx和pxd文件。

更糟糕的工作是在导入时重命名atexit模块：import atexit as ae。