当没有默认构造函数和唯一指针时，Boost.Python 库构建错误

Question

我正在尝试使用 Boost.Python 来包装我的 C++ 代码，但遇到了一些错误，我可以使用一些帮助来解决它们。但首先是我拥有的资产。

Product.h

namespace Products
{
  class Product
  {
  public:
    virtual ~Product() {};
    virtual int generateProduct(int verbose = 0) = 0;
    virtual int getQueueNum() = 0;
    virtual std::vector<std::vector<std::string> > getQueue(const int &index_int) = 0;
  };
}

ProductBuilder.h

namespace Products
{
  class ProductBuilder
  {
  public:
    ProductBuilder(const std::map<std::string,std::string> input_map, const std::deque<std::string> &dates_deque);
    int build(int verbose = 0);
    int numQueue() {return m_product->getQueueNum();};
    std::vector<std::vector<std::string> > getQueueByIndex(const int &index_int) {return m_product->getQueue(index_int);};
  private:
    std::unique_ptr<Products::Product> m_product;
  };
}

full-wrapper.cpp

BOOST_PYTHON_MODULE(alucard)
  {
    class_<Products::ProductBuilder>("ProductBuilder", init<std::map<std::string,std::string>,std::deque<std::string>>())
    .def("build", &Products::ProductBuilder::build)
    .def("numQueue", &Products::ProductBuilder::numQueue)
    .def("getQueueByIndex", &Products::ProductBuilder::getQueueByIndex)
    ;
  }

我通过 cmake 构建库时遇到的错误如下：

/usr/include/boost/python/object/value_holder.hpp:133:13: error: use of deleted function ‘Products::ProductBuilder::ProductBuilder(const Products::ProductBuilder&)’
             BOOST_PP_REPEAT_1ST(N, BOOST_PYTHON_UNFORWARD_LOCAL, nil)
             ^
In file included from /home/jlahowetz2/development/cpp-python-wrapper/full-wrapper.cpp:11:0:
/data/alucard/include/ProductBuilder.h:25:9: note: ‘Products::ProductBuilder::ProductBuilder(const Products::ProductBuilder&)’ is implicitly deleted because the default definition would be ill-formed:
   class ProductBuilder
         ^~~~~~~~~~~~~~
/data/alucard/include/ProductBuilder.h:25:9: error: use of deleted function ‘std::unique_ptr<_Tp, _Dp>::unique_ptr(const std::unique_ptr<_Tp, _Dp>&) [with _Tp = Products::Product; _Dp = std::default_delete<Products::Product>]’
In file included from /usr/include/c++/7/memory:80:0,
                 from /usr/include/boost/function/function_base.hpp:16,
                 from /usr/include/boost/function/detail/prologue.hpp:17,
                 from /usr/include/boost/function/function_template.hpp:13,
                 from /usr/include/boost/function/detail/maybe_include.hpp:13,
                 from /usr/include/boost/function/function0.hpp:11,
                 from /usr/include/boost/python/errors.hpp:13,
                 from /usr/include/boost/python/handle.hpp:11,
                 from /usr/include/boost/python/args_fwd.hpp:10,
                 from /usr/include/boost/python/args.hpp:10,
                 from /usr/include/boost/python.hpp:11,
                 from /home/jlahowetz2/development/cpp-python-wrapper/full-wrapper.cpp:1:
/usr/include/c++/7/bits/unique_ptr.h:383:7: note: declared here
       unique_ptr(const unique_ptr&) = delete;
       ^~~~~~~~~~

Answer 1

显然 Python 代码复制了您的 ProductBuilder 对象。但是，ProductBuilder 包含一个 unique_ptr，它不能被复制（它只能被移动）。解决此问题的一种简单方法是将 unique_ptr 替换为可复制的 shared_ptr。