Question

我从v8 3.x迁移到4.y，并且我在其中一个头文件中定义了其中一个函数时出现问题。

//JavascriptBase.h
namespace Company {
    class Base {
      protected:
        void registerHandler(v8::Persistent<v8::Function>& func) {
            user_functions_.push_back(func);
        }
      private:
        std::vector<v8::Persistent<v8::Function>> user_functions_;
    }
}

当我尝试编译时，我收到以下错误：

third-party2/v8/4.7.39/gcc-4.8.1-glibc-2.17-fb/281a9e6/include/v8.h:667:53: error: assigning to 'v8::Object *volatile' from incompatible type 'v8::Primitive *'
    while (false) { *(static_cast<O* volatile*>(0)) = static_cast<Primitive*>(0); };
                                                    ^ ~~~~~~~~~~~~~~~~~~~~~~~~~~
third-party2/v8/4.7.39/gcc-4.8.1-glibc-2.17-fb/281a9e6/include/v8.h:663:5: note: in instantiation of function template specialization 'v8::NonCopyablePersistentTraits<v8::Function>::Uncompilable<v8::Object>' requested here
    Uncompilable<Object>();
    ^
third-party2/v8/4.7.39/gcc-4.8.1-glibc-2.17-fb/281a9e6/include/v8.h:7175:6: note: in instantiation of function template specialization 'v8::NonCopyablePersistentTraits<v8::Function>::Copy<v8::Function, v8::NonCopyablePersistentTraits<v8::Function> >' requested here
  M::Copy(that, this);
     ^
third-party2/v8/4.7.39/gcc-4.8.1-glibc-2.17-fb/281a9e6/include/v8.h:729:5: note: in instantiation of function template specialization 'v8::Persistent<v8::Function, v8::NonCopyablePersistentTraits<v8::Function> >::Copy<v8::Function, v8::NonCopyablePersistentTraits<v8::Function> >' requested here
    Copy(that);
    ^
third-party2/libgcc/4.8.1/gcc-4.8.1-glibc-2.17-fb/8aac7fc/include/c++/4.8.1/ext/new_allocator.h:120:23: note: in instantiation of member function 'v8::Persistent<v8::Function, v8::NonCopyablePersistentTraits<v8::Function> >::Persistent' requested here
 { ::new((void *)__p) _Up(std::forward<_Args>(__args)...); }
                      ^
third-party2/libgcc/4.8.1/gcc-4.8.1-glibc-2.17-fb/8aac7fc/include/c++/4.8.1/bits/alloc_traits.h:254:8: note: in instantiation of function template specialization '__gnu_cxx::new_allocator<v8::Persistent<v8::Function, v8::NonCopyablePersistentTraits<v8::Function> > >::construct<v8::Persistent<v8::Function, v8::NonCopyablePersistentTraits<v8::Function> >, const v8::Persistent<v8::Function, v8::NonCopyablePersistentTraits<v8::Function> > &>' requested here
 { __a.construct(__p, std::forward<_Args>(__args)...); }
       ^
third-party2/libgcc/4.8.1/gcc-4.8.1-glibc-2.17-fb/8aac7fc/include/c++/4.8.1/bits/alloc_traits.h:393:4: note: in instantiation of function template specialization 'std::allocator_traits<std::allocator<v8::Persistent<v8::Function, v8::NonCopyablePersistentTraits<v8::Function> > > >::_S_construct<v8::Persistent<v8::Function, v8::NonCopyablePersistentTraits<v8::Function> >, const v8::Persistent<v8::Function, v8::NonCopyablePersistentTraits<v8::Function> > &>' requested here
 { _S_construct(__a, __p, std::forward<_Args>(__args)...); }
   ^
third-party2/libgcc/4.8.1/gcc-4.8.1-glibc-2.17-fb/8aac7fc/include/c++/4.8.1/bits/stl_vector.h:905:21: note: in instantiation of function template specialization 'std::allocator_traits<std::allocator<v8::Persistent<v8::Function, v8::NonCopyablePersistentTraits<v8::Function> > > >::construct<v8::Persistent<v8::Function, v8::NonCopyablePersistentTraits<v8::Function> >, const v8::Persistent<v8::Function, v8::NonCopyablePersistentTraits<v8::Function> > &>' requested here
     _Alloc_traits::construct(this->_M_impl, this->_M_impl._M_finish,
                    ^
./Company/JavaScriptBase.h:84:21: note: in instantiation of member function 'std::vector<v8::Persistent<v8::Function, v8::NonCopyablePersistentTraits<v8::Function> >, std::allocator<v8::Persistent<v8::Function, v8::NonCopyablePersistentTraits<v8::Function> > > >::push_back' requested here
    user_functions_.push_back(func);
                    ^
1 error generated.

我已经完成了一些谷歌搜索，发现Persistent个对象不可分配，但我不知道如何处理这些信息。任何帮助将不胜感激。

Answer 1

如果它们不可分配，那么你（显然）不能分配它们。由于std::vector<>依赖于使用赋值运算符复制值，因此您的方法将无效。

然而，您可以存储指针，因为复制指针的任何内容都已明确定义。

Answer 2

您可以使用此“typedef”

创建可复制的持久性

using CopyablePersistent = v8::Persistent<T, v8::CopyablePersistentTraits<T>>;

这假设它在一个模板化的类中，但你可以随心所欲地制作T.

编辑：显然这是一个“非常糟糕”的事情，但我不知道为什么。

无法将持久<function>添加到vector <persistent <function>＆gt;

2 个答案: