在Cython中调用外部c ++模板函数
我有一些c ++模板函数在c ++头文件中声明和实现，我想访问Cython中的一些函数。
假设c ++代码位于header.hpp ，如下所示
template <class T>
T doublit(T& x) {
return 2*x;
}
我需要在.pyx文件和setup.py文件中写入什么内容才能使用Python中的函数
>>> import modname
>>> print modname.doublit(3)
6
PS：是否可以在PYPY中访问相同的功能？ 如果是，如何？
感谢您的帮助。 但当我试图按照自己的方式行事时，我遇到了更多的困难（下文）。
doublit.h
template <class T>
T doublit(T& x) {
return 2*x;
}
cdoublit.pxd
cdef extern from "doublit.h":
cdef int doublit1 "doublit<int>"(int& foo)
cdef double doublit2 "doublit<double>"(double& foo)
doublit.pyx
# main.pyx file
from cdoublit cimport *
cdef int n1 = 5
cdef double n2 = 5.0
print(doublit1(n1))
print(doublit2(n2))
和setup.py
from distutils.core import setup
from distutils.extension import Extension
from Cython.Distutils import build_ext
ext_modules = [Extension("doublit", ["doublit.pyx"])]
setup(
name = 'Learning Cython',
cmdclass = {'build_ext': build_ext},
ext_modules = ext_modules
)
最后，我建立为
>>> python setup.py build_ext --inplace
但我得到以下例外：
###:doublit markma$ python setup.py build_ext --inplace
running build_ext
cythoning doublit.pyx to doublit.c
building 'doublit' extension
creating build
creating build/temp.macosx-10.6-intel-2.7
gcc-4.2 -fno-strict-aliasing -fno-common -dynamic -isysroot /Developer/SDKs/MacOSX10.6.sdk -arch i386 -arch x86_64 -g -O2 -DNDEBUG -g -O3 -I/Library/Frameworks/Python.framework/Versions/2.7/include/python2.7 -c doublit.c -o build/temp.macosx-10.6-intel-2.7/doublit.o
In file included from doublit.c:311:
doublit.h:1: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘<’ token
doublit.c: In function ‘initdoublit’:
doublit.c:782: error: ‘doublit’ undeclared (first use in this function)
doublit.c:782: error: (Each undeclared identifier is reported only once
doublit.c:782: error: for each function it appears in.)
doublit.c:782: error: expected expression before ‘int’
doublit.c:793: error: expected expression before ‘double’
In file included from doublit.c:311:
doublit.h:1: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘<’ token
doublit.c: In function ‘initdoublit’:
doublit.c:782: error: ‘doublit’ undeclared (first use in this function)
doublit.c:782: error: (Each undeclared identifier is reported only once
doublit.c:782: error: for each function it appears in.)
doublit.c:782: error: expected expression before ‘int’
doublit.c:793: error: expected expression before ‘double’
lipo: can't figure out the architecture type of: /var/folders/ip/ip5rkteZFbWPEtzhmxRdVE+++Tc/-Tmp-//ccvaEGqZ.out
error: command 'gcc-4.2' failed with exit status 1
Cython支持模板语法，但仅限于类（从Cython 0.19.1开始）。
尽管您可以使用以下语法来包装模板函数：
# doublit.pxd file
cdef extern from "doublit.h":
cdef int doublit1 "doublit<int>"(int& foo)
cdef double doublit2 "doublit<double>"(double& foo)
# main.pyx file
from doublit cimport *
cdef int n1 = 5
cdef double n2 = 5.0
print(doublit1(n1))
print(doublit2(n2))
你失去了自动化，但至少你可以让它工作。
UPDATE
Cython 0.20增加了对调用C ++模板函数的支持。 Cython 0.20测试版发布。
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