numpy ctypes“动态模块未定义初始化函数".如果每次都不重新编译，则报错

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问题描述

很抱歉，还有关于dynamic module does not define init function的其他问题.我确实遇到了一些较早的问题，但没有找到一个能完全满足我的情况的问题.

sorry for yet an other question about dynamic module does not define init function. I did go through older questions but I didn't find one which adress my case specifically enought.

我有一个C ++库，该库应该将多个函数导出到python(如extern "C" {}块中定义的〜5个函数).每次导入库时，只要重新编译该库，它就可以正常工作.但是，如果我不重新编译就将其导入，则会出现错误ImportError: dynamic module does not define init function (initmylib)

I have a C++ library which should export several functions to python ( like ~5 functions defined in extern "C" {} block ). It works just fine when I recompile the library each time I import it. However, if I import it without recompilation it gives error ImportError: dynamic module does not define init function (initmylib)

非常简单的示例再现了相同的行为(错误)，如下所示:

The very simplified example which reproduce the same behaviour (error) looks like this:

文件mylib.cpp

#include <math.h>
// there are some internal C++ functions and classes 
// which are not exported, but used in exported functions
extern "C"{
// one of the functions which should be accessible from python
void oscilator( double dt, int n, double * abuff, double * bbuff ){
    double a = abuff[0];
    double b = bbuff[0];
    for (int i=1; i<n; i++){
        a = a - b*dt;
        b = b + a*dt;
        abuff[i] = a;
        bbuff[i] = b;
    }
}
// there are also other functions but let's keep this example simple
// int initmylib( ){ return 0; } // some junk ... if this makes ctypes happy ?
}

C ++库mylib.cpp的

python warper mylib.py:

import numpy as np
from   ctypes import c_int, c_double
import ctypes
import os

name='mylib'
ext='.so'  # if compited on linux .so on windows .dll

def recompile( 
        LFLAGS="",
        #FFLAGS="-Og -g -Wall"
        FFLAGS="-std=c++11 -O3 -ffast-math -ftree-vectorize"
    ):
    import os
    print " ===== COMPILATION OF : "+name+".cpp"
    print  os.getcwd()
    os.system("g++ "+FFLAGS+" -c -fPIC "+name+".cpp -o "+name+".o"+LFLAGS)
    os.system("g++ "+FFLAGS+" -shared -Wl,-soname,"+name+ext+" -o "+name+ext+" "+name+".o"+LFLAGS)

# this will recompile the library if somebody delete it
if not os.path.exists("./"+name+ext ):
    recompile()

lib    = ctypes.CDLL("./"+name+ext )

array1d = np.ctypeslib.ndpointer(dtype=np.double, ndim=1, flags='CONTIGUOUS')

# void oscilator( double dt, int n, double * abuff, double * bbuff )
lib.oscilator.argtypes = [ c_double, c_int, array1d, array1d ]
lib.oscilator.restype  = None
def oscilator( dt, a, b ):
    n  = len(a)
    lib.oscilator( dt, n, a, b )

导入mylib

import os
from pylab import *
from basUtils import * 

# this will delete all compiled files of the library to force recompilation
def makeclean( ):
    [ os.remove(f) for f in os.listdir(".") if f.endswith(".so") ]
    [ os.remove(f) for f in os.listdir(".") if f.endswith(".o") ]
    [ os.remove(f) for f in os.listdir(".") if f.endswith(".pyc") ]

# if I do makeclean() every time it works, if I do not it does not
#makeclean( )

import mylib

a=zeros(100)
b=zeros(100)
a[0] = 1

mylib.oscilator( 0.1, a, b )

plot( a )
plot( b )

show()

我还试图通过在mylib.cpp中添加一些int initmylib( ){ return 0; }函数来使ctypes满意，如上面的代码所示.但这会产生错误SystemError: dynamic module not initialized properly

I was also trying to make ctypes happy by adding some int initmylib( ){ return 0; } function into mylib.cpp as you can see in the code above. however this will produce error SystemError: dynamic module not initialized properly

当我编译 cos_doubles 从scipy讲义中摘录.但是，此示例仅在我只想导入一个与库名称相同的函数时才有效.我想要更一般的东西.

I don't have this issue when I compile example of cos_doubles from scipy lecture notes. However, this example works only If I want to import just one function with the same name as the name of the library. I want something more general.

myLib

numpy ctypes“动态模块未定义初始化函数".如果每次都不重新编译，则报错

问题描述

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