在Python中继承c++的Base，使用SWIG调用抽象方法

我有一些麻烦耦合c++(98)与python 3。我在c++中有一些基类，我想在Python中扩展。一些有问题的方法在c++端是纯虚的，因此将在Python端实现。

目前，我可以从c++中调用抽象方法，通过swig，在Python中调用专门化。酷。我在向Python传递参数时遇到了麻烦。

简化问题的最小完整示例:

// iBase.h
#pragma once
#include <memory>
typedef enum EMyEnumeration{
    EMyEnumeration_Zero,
    EMyEnumeration_One,
    EMyEnumeration_Two
}TEMyEnumeration;

class FooBase{
protected:  
    int a;
public:
    virtual int getA() = 0 ; 
};
class Foo : public FooBase{
public:
    Foo() {a = 2;}
    int getA(){return a;}
};
class iBase{
    public:
    virtual void start() =0;
    virtual void run(std::shared_ptr<FooBase> p, TEMyEnumeration enumCode) = 0;
};

右边:

// myif.i
%module(directors="1") DllWrapper
%{
#include <iostream>
#include "iBase.h"
%}
%include <std_shared_ptr.i>
%shared_ptr(FooBase)
%shared_ptr(Foo)
%feature("director") FooBase;
%feature("director") iBase;
%include "iBase.h"

运行swig as:

swig -c++ -python myif.i
swig -Wall -c++ -python -external-runtime runtime.h

myif_wrap编译。cxx -> _DllWrapper。pyd

用下面的代码创建一个*.exe，它将加载_DllWrapper。Pyd库(确保它在同一个目录中!)。同时，将swig生成的DllWrapper.py拷贝到exe目录。

//Main_SmartPtr.cpp
#include "stdafx.h"
#include <Python.h>
#include <windows.h> 
#include <string>
#include <memory>
#include "iBase.h"
#include "runtime.h"
using namespace std;
int _tmain(int argc, _TCHAR* argv[])
{
    string moduleName = "ExampleSmartPtr";
    // load *.pyd  (actually a dll file which implements PyInit__<swigWrapperName>)
    auto handle =LoadLibrary("_DllWrapper.pyd");
    // getting an instance handle..
    Py_Initialize();
    PyObject *main = PyImport_AddModule("__main__");
    PyObject *dict = PyModule_GetDict(main);
    PyObject *module = PyImport_Import(PyString_FromString(moduleName.c_str()));
    PyModule_AddObject(main, moduleName.c_str(), module);
    PyObject *instance = PyRun_String(string(moduleName+string(".")+moduleName+string("()")).c_str(), Py_eval_input, dict, dict);

    //calling start() in the Python derived class..
    //PyObject *result = PyObject_CallMethod(instance, "start", (char *)"()");
    // trying to call run in the Python derived class..
    shared_ptr<Foo> foo = make_shared<Foo>();
    EMyEnumeration enumCode = EMyEnumeration_Two;

    string  typeName1 = "std::shared_ptr <FooBase> *"; 
    swig_type_info* info1 = SWIG_TypeQuery(typeName1.c_str());
    auto swigData1 = SWIG_NewPointerObj((void*)(&foo), info1, SWIG_POINTER_OWN);
    string  typeName2 = "TEMyEnumeration *"; 
    swig_type_info* info2 = SWIG_TypeQuery(typeName2.c_str());
    auto swigData2 = SWIG_NewPointerObj((void*)(&enumCode), info2, SWIG_POINTER_OWN);
    auto result = PyObject_CallMethod(instance, "run", (char *)"(O)(O)", swigData1, swigData2);
    return 0;
}

创建一个新的Python文件，并把它放在exe的目录下:

#ExampleSmartPtr.py
import DllWrapper
class ExampleSmartPtr(DllWrapper.iBase):
    def __init__(self): # constructor
        print("__init__!!")
        DllWrapper.iBase.__init__(self)
    def start(self):
        print("start")
        return 0
    def run(self, data, enumCode):
        print("run")
        print("-> data: "+str(data))
        print("-> enumCode: "+str(enumCode))
        print (data.getA())
        return 1

运行exe的输出为:

__init__!!
run
-> data: (<DllWrapper.FooBase; proxy of <Swig Object of type 'std::shared_ptr< FooBase > *' at 0x00000000014F8B70> >,)
-> enumCode: (<Swig Object of type 'TEMyEnumeration *' at 0x00000000014F89F0>,)

如何"解引用"enumCode到一个简单的int?如何在python类run()中调用print (data.getA()) ?在当前的形式下，它不打印任何东西。

import ExampleSmartPtr
instance = ExampleSmartPtr.ExampleSmartPtr()
swigData1 = ExampleSmartPtr.DllWrapper.Foo()
swigData2 = ExampleSmartPtr.DllWrapper.EMyEnumeration_Two
instance.run(swigData1,swigData2)

__init__!!
run
-> data: <DllWrapper.Foo; proxy of <Swig Object of type 'std::shared_ptr< Foo > *' at 0x7f8825c0b7e0> >
-> enumCode: 2

iBase *python2interface(PyObject *obj) {
  void *argp1 = 0;
  swig_type_info * pTypeInfo = SWIG_TypeQuery("iBase *");
  const int res = SWIG_ConvertPtr(obj, &argp1,pTypeInfo, 0);
  if (!SWIG_IsOK(res)) {
    abort();
  }
  return reinterpret_cast<iBase*>(argp1);
}

auto foo = make_shared<Foo>();
TEMyEnumeration enumCode = EMyEnumeration_Two;
python2interface(instance)->run(foo, enumCode);