添加swig pythoncode在Python对象上设置thisown标志

我有一个swigged C类容器,MyContainer,持有MyObject类型的对象,也是一个C类. 以下是C头代码(freemenot.h) #ifndef freemenotH #define freemenotH #include <vector> #include <string> using std::string; class MyObject { public: MyObject(const string& lbl); ~MyObject(); string getLabel(); private: string label; }; class MyContainer { public: MyContainer(); ~MyContainer(); void addObject(MyObject* o); MyObject* getObject(unsigned int t); int getNrOfObjects(); private: std::vector<MyObject*> mObjects; }; #endif 这是源(freemenot.cpp) #include "freemenot.h" #include <iostream> using namespace std; /* MyObject source */ MyObject::MyObject(const string& lbl) : label(lbl) { cout<<"In object ctor"<<endl; } MyObject::~MyObject() { cout<<"In object dtor"<<endl; } string MyObject::getLabel() { return label; } /* MyContainer source */ MyContainer::MyContainer() { cout<<"In container ctor"<<endl; } MyContainer::~MyContainer() { cout<<"In container dtor"<<endl; for(unsigned int i = 0; i < mObjects.size(); i++) { delete mObjects[i]; } } int MyContainer::getNrOfObjects() { return mObjects.size(); } void MyContainer::addObject(MyObject* o) { mObjects.push_back(o); } MyObject* MyContainer::getObject(unsigned int i) { return mObjects[i]; } 观察对象在向量中存储为RAW POINTERS.这个类是这样设计的,因此容器负责释放析构函数中的对象,就像在循环的析构函数中完成一样. 在C代码中,如下所示,将对象o1添加到容器c中,该对象返回到客户端代码 MyContainer* getAContainerWithSomeObjects() { MyContainer* c = new MyContainer(); MyObject* o1 = new MyObject(); c.add(o1); return c; } 返回的容器拥有其对象,并在完成后负责取消分配这些对象.在C中,在函数退出之后访问容器对象就可以了. 使用Swig将上述类公开给python将需要一个接口文件.此接口文件如下所示 %module freemenot %{ #include "freemenot.h" %} %include "std_string.i" //Expose to Python %include "freemenot.h" 为了使用CMake生成Python模块,使用了以下CMake脚本. cmake_minimum_required(VERSION 2.8) project(freemenot) find_package(SWIG REQUIRED) include(UseSWIG) find_package(PythonInterp) find_package(PythonLibs) get_filename_component(PYTHON_LIB_FOLDER ${PYTHON_LIBRARIES} DIRECTORY CACHE) message("Python lib folder: " ${PYTHON_LIB_FOLDER}) message("Python include folder: " ${PYTHON_INCLUDE_DIRS}) message("Python libraries: " ${PYTHON_LIBRARIES}) set(PyModule "freemenot") include_directories( ${PYTHON_INCLUDE_PATH} ${CMAKE_CURRENT_SOURCE_DIR} ) link_directories( ${PYTHON_LIB_FOLDER}) set(CMAKE_MODULE_LINKER_FLAGS ${CMAKE_CURRENT_SOURCE_DIR}/${PyModule}.def) set_source_files_properties(${PyModule}.i PROPERTIES CPLUSPLUS ON) set_source_files_properties(${PyModule}.i PROPERTIES SWIG_FLAGS "-threads") SWIG_ADD_LIBRARY(${PyModule} MODULE LANGUAGE python SOURCES ${PyModule}.i freemenot.cpp) SWIG_LINK_LIBRARIES (${PyModule} ${PYTHON_LIB_FOLDER}/Python37_CG.lib ) # INSTALL PYTHON BINDINGS # Get the python site packages directory by invoking python execute_process(COMMAND python -c "import site; print(site.getsitepackages()[0])" OUTPUT_VARIABLE PYTHON_SITE_PACKAGES OUTPUT_STRIP_TRAILING_WHITESPACE) message("PYTHON_SITE_PACKAGES = ${PYTHON_SITE_PACKAGES}") install( TARGETS _${PyModule} DESTINATION ${PYTHON_SITE_PACKAGES}) install( FILES ${CMAKE_CURRENT_BINARY_DIR}/${PyModule}.py DESTINATION ${PYTHON_SITE_PACKAGES} ) 使用CMake生成make文件,并使用borlands bcc32编译器进行编译,生成Python模块(freemenot)并将其安装到python3有效的sitepackages文件夹中. 然后,在Python中,可以使用以下脚本来说明问题 import freemenot as fmn def getContainer(): c = fmn.MyContainer() o1 = fmn.MyObject("This is a label") o1.thisown = 0 c.addObject(o1) return c c = getContainer() print (c.getNrOfObjects()) #if the thisown flag for objects in the getContainer function #is equal to 1, the following call return an undefined object #If the flag is equal to 0, the following call will return a valid object a = c.getObject(0) print (a.getLabel()) 这个Python代码可能看起来很好,但不能按预期工作.问题是,当函数getContainer()返回时,如果thisown标志未设置为零,则释放对象o1的内存.使用返回的容器访问该行之后的对象将最终导致灾难.请注意,这本身没有任何问题,因为这是pythons垃圾收集的工作原理. 对于上面的用例,能够在addObject函数中设置python对象thisown标志,将呈现在Python中可用的C对象.让用户设置此标志不是一个好的解决方案.还可以使用“addObject”函数扩展python类,并修改此函数内的thisown标志,从而隐藏用户的这种内存技巧. 问题是,如何在没有扩展课程的情况下让Swig这样做？我正在寻找使用类型图,或者可能是％pythoncode,但我似乎无法找到一个好的工作示例. 上面的代码将被一个调用Python解释器的C程序使用并传递给它. C程序负责管理python函数中分配的内存,即使在PyFinalize()之后也是如此. 上面的代码可以从github https://github.com/TotteKarlsson/miniprojects下载