在模板类中定义的类型“不命名类型” [英] Type defined in template class "does not name a type"

问题描述

几个星期前我开始使用范本，我在使用时遇到问题。
我得到这个错误：

Freestyle / _gl /../_ convection_selective / Definitions.h：153：9：error：' Node_handle 'in 'Point_set {aka struct Kd_tree_patch>> *，My_point_property_map，CGAL :: Search_traits>>，const double *，Construct_coord_iterator> strong>Definitions.h：时，

  #includeKd_tree_patch.h
 [...] 
 template< class SearchTraits， class Splitter_ = CGAL :: Sliding_midpoint< SearchTraits>，UseExtendedNode = CGAL :: Tag_true> class Kd_tree_patch; // forward declaration 
 
 typedef Kd_tree_patch< Search_traits> Point_set; 
 typedef Point_set :: Node_handle Node_handle; 
  

Kd_tree_patch.h：

  template< class SearchTraits，class Splitter_ = Sliding_midpoint< SearchTraits> ;, class UseExtendedNode = Tag_true> 
 class Kd_tree_patch {
 [...] 
 typedef Kd_tree_node< SearchTraits，Splitter，UseExtendedNode>节点; 
 typedef typename Compact_container< Node> :: iterator Node_handle; 
}; 
  

为什么Node_handle不被视为类型？

感谢您的帮助。

解决方案

您无法转发声明嵌套类型，嵌套类型 Node_handle ，模板 Kd_tree_patch 必须在之前定义 typedef。一旦你解决了，你还需要通过使用 typename 指示编译器它是一个类型：

  typedef typename Point_set :: Node_handle Node_handle; 
 // ^^^^^^^^ 
  

I began to use templates a few weeks ago, and I'm having trouble using it. I got this error :

Freestyle/_gl/../_convection_selective/Definitions.h:153:9: error: ‘Node_handle’ in ‘Point_set {aka struct Kd_tree_patch > >*, My_point_property_map, CGAL::Search_traits > >, const double*, Construct_coord_iterator> > >}’ does not name a type

while compiling this code:

"Definitions.h":

#include "Kd_tree_patch.h"
[...]
template <class SearchTraits, class Splitter_= CGAL::Sliding_midpoint<SearchTraits>, class UseExtendedNode = CGAL::Tag_true > class Kd_tree_patch;  //forward declaration

typedef Kd_tree_patch<Search_traits> Point_set;    
typedef Point_set::Node_handle Node_handle;

"Kd_tree_patch.h":

template <class SearchTraits, class Splitter_=Sliding_midpoint<SearchTraits>, class UseExtendedNode = Tag_true >
class Kd_tree_patch {
[...]
typedef Kd_tree_node<SearchTraits, Splitter, UseExtendedNode > Node;
typedef typename Compact_container<Node>::iterator Node_handle;
};

Why Node_handle isn't considered as a type yet ?

Thanks for your help.

解决方案

You cannot forward declare nested types, which means that to be able to use the nested type Node_handle, the template Kd_tree_patch must be defined before the typedef. Once you fix that, you will also need to instruct the compiler that it is a type through the use of typename:

typedef typename Point_set::Node_handle Node_handle;
//      ^^^^^^^^

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