python中封装一个枚举_使用Boost-Python包装枚举

AttributeError是尝试在没有第一个设置范围的情况下创建Python扩展类型的结果. boost::python::enum_构造函数指出：

Constructs an enum_ object holding a Python extension type derived from int which is named name. The named attribute of the current scope is bound to the new extension type.

嵌入Python时,要使用自定义Python模块,通常最容易使用PyImport_AppendInittab,然后按名称导入该模块.

PyImport_AppendInittab("example", &initexample);

...

boost::python::object example = boost::python::import("example");

这是一个完整的示例,显示了通过Boost.Python公开的两个枚举.一个包含在由main导入的单独模块(示例)中,另一个则直接在main中公开.

#include

#include

/// @brief Mockup class with a nested enum.

struct TestClass

{

/// @brief Mocked enum.

enum Motion

{

walk,

bike

};

// @brief Mocked enum.

enum Color

{

red,

blue

};

};

/// @brief Python example module.

BOOST_PYTHON_MODULE(example)

{

namespace python = boost::python;

python::enum_<:motion>("Motion")

.value("walk", TestClass::walk)

.value("bike", TestClass::bike)

;

}

int main()

{

PyImport_AppendInittab("example", &initexample); // Add example to built-in.

Py_Initialize(); // Start interpreter.

// Create the __main__ module.

namespace python = boost::python;

try

{

python::object main = python::import("__main__");

python::object main_namespace = main.attr("__dict__");

python::scope scope(main); // Force main scope

// Expose TestClass::Color as Color

python::enum_<:color>("Color")

.value("red", TestClass::red)

.value("blue", TestClass::blue)

;

// Print values of Color enumeration.

python::exec(

"print Color.values",

main_namespace, main_namespace);

// Get a handle to the Color enumeration.

python::object color = main_namespace["Color"];

python::object blue = color.attr("blue");

if (TestClass::blue == python::extract<:color>(blue))

std::cout << "blue enum values matched." << std::endl;

// Import example module into main namespace.

main_namespace["example"] = python::import("example");

// Print the values of the Motion enumeration.

python::exec(

"print example.Motion.values",

main_namespace, main_namespace);

// Check if the Python enums match the C++ enum values.

if (TestClass::bike == python::extract<:motion>(

main_namespace["example"].attr("Motion").attr("bike")))

std::cout << "bike enum values matched." << std::endl;

}

catch (const python::error_already_set&)

{

PyErr_Print();

}

}

输出：

{0: __main__.Color.red, 1: __main__.Color.blue}

blue enum values matched.

{0: example.Motion.walk, 1: example.Motion.bike}

bike enum values matched.