扩展 boost::文件系统::p ath 和重载赋值运算符

Extending on boost::filesystem::path and overloading assignment operator

本文关键字：重载 ath 赋值运算符 boost 文件系统 扩展      更新时间：2023-10-16

我知道已经有几个主题与重载基类的复制和赋值运算符有关 - 但是经过两天的尝试，我无法使用boost：：filesystem：:p ath正确执行此操作。

我目前拥有的：

using namespace boost::filesystem;
class MyPath: public path
{
  public:
    template<class C>
    MyPath(const C* p): path(p)// dispatch to base copy constructor
    {
      //http://stackoverflow.com/questions/1226634/how-to-use-base-classs-constructors-and-assignment-operator-in-c
      //this one seems to be OK
    }
    MyPath& operator=(const MyPath& p)
    {
      path::operator=(p);
      return *this;
    }
    bool myStuff(){/*...*/}
    /* ... */
}

然后，我使用 MyPath 类，就像之前的"path"一样：

using namespace std;
using namespace boost::filesystem;
list<MyPath> files_list;
MyPath input_folder("a valid path");
copy(recursive_directory_iterator(input_folder), recursive_directory_iterator(), back_inserter(files_list));

这段代码在 path 上工作正常，但在 MyPath 中，我在赋值运算符方面遇到了问题，我还没有弄清楚 std：：list 和迭代器需要的运算符 = 的格式是什么。

g++ -g -Ic:/mingw/include -c main.cpp
In file included from c:mingwincludec++4.8.1bitschar_traits.h:39:0,
                 from c:mingwincludec++4.8.1ios:40,
                 from c:mingwincludec++4.8.1ostream:38,
                 from c:mingwincludec++4.8.1iostream:39,
                 from main.cpp:1:
c:mingwincludec++4.8.1bitsstl_algobase.h: In instantiation of 'static _OI std::__copy_move<<anonymous>, <anonymous>, <template-parameter-1-3> >::__copy_m(_II, _II, _OI) [with _II =     boost::filesystem::recursive_directory_iterator; _OI = std::back_insert_iterator<std::list<MyPath> >; bool <anonymous> = false; bool <anonymous> = false; <template-parameter-1-3> = std::input_iterator_tag]':
c:mingwincludec++4.8.1bitsstl_algobase.h:390:70:   required from '_OI std::__copy_move_a(_II, _II, _OI) [with bool _IsMove = false; _II = boost::filesystem::recursive_directory_iterator; _OI =     std::back_insert_iterator<std::list<MyPath> >]'
c:mingwincludec++4.8.1bitsstl_algobase.h:428:38:   required from '_OI std::__copy_move_a2(_II, _II, _OI) [with bool _IsMove = false; _II = boost::filesystem::recursive_directory_iterator; _OI =     std::back_insert_iterator<std::list<MyPath> >]'
c:mingwincludec++4.8.1bitsstl_algobase.h:460:17:   required from '_OI std::copy(_II, _II, _OI) [with _II = boost::filesystem::recursive_directory_iterator; _OI = std::back_insert_iterator<std::list<    MyPath> >]'
main.cpp:23:115:   required from here
c:mingwincludec++4.8.1bitsstl_algobase.h:305:16: error: no match for 'operator=' (operand types are 'std::back_insert_iterator<std::list<MyPath> >' and 'boost::filesystem::directory_entry')
      *__result = *__first;
                ^
c:mingwincludec++4.8.1bitsstl_algobase.h:305:16: note: candidates are:
In file included from c:mingwincludec++4.8.1bitsstl_algobase.h:67:0,
                 from c:mingwincludec++4.8.1bitschar_traits.h:39,
                 from c:mingwincludec++4.8.1ios:40,
                 from c:mingwincludec++4.8.1ostream:38,
                 from c:mingwincludec++4.8.1iostream:39,
                 from main.cpp:1:
c:mingwincludec++4.8.1bitsstl_iterator.h:436:7: note: std::back_insert_iterator<_Container>& std::back_insert_iterator<_Container>::operator=(const typename _Container::value_type&) [with _Container =     std::list<MyPath>; typename _Container::value_type = MyPath]
       operator=(const typename _Container::value_type& __value)
       ^
c:mingwincludec++4.8.1bitsstl_iterator.h:436:7: note:   no known conversion for argument 1 from 'boost::filesystem::directory_entry' to 'const value_type& {aka const MyPath&}'
c:mingwincludec++4.8.1bitsstl_iterator.h:443:7: note: std::back_insert_iterator<_Container>& std::back_insert_iterator<_Container>::operator=(typename _Container::value_type&&) [with _Container =     std::list<MyPath>; typename _Container::value_type = MyPath]
       operator=(typename _Container::value_type&& __value)
       ^
c:mingwincludec++4.8.1bitsstl_iterator.h:443:7: note:   no known conversion for argument 1 from 'boost::filesystem::directory_entry' to 'std::list<MyPath>::value_type&& {aka MyPath&&}'
c:mingwincludec++4.8.1bitsstl_iterator.h:402:11: note: std::back_insert_iterator<std::list<MyPath> >& std::back_insert_iterator<std::list<MyPath> >::operator=(const std::back_insert_iterator<std::list<    MyPath> >&)
     class back_insert_iterator
           ^
c:mingwincludec++4.8.1bitsstl_iterator.h:402:11: note:   no known conversion for argument 1 from 'boost::filesystem::directory_entry' to 'const std::back_insert_iterator<std::list<MyPath> >&'
c:mingwincludec++4.8.1bitsstl_iterator.h:402:11: note: std::back_insert_iterator<std::list<MyPath> >& std::back_insert_iterator<std::list<MyPath> >::operator=(std::back_insert_iterator<std::list<MyPath>     >&&)
c:mingwincludec++4.8.1bitsstl_iterator.h:402:11: note:   no known conversion for argument 1 from 'boost::filesystem::directory_entry' to 'std::back_insert_iterator<std::list<MyPath> >&&'
make: *** [main.o] Error 1

编译器会告诉你你需要什么：

'operator=' (operand types are 'std::back_insert_iterator<std::list<MyPath> >' and 'boost::filesystem::directory_entry')

所以你需要再实现一种方法（至少）。

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