[英]C++ inheritance error when creating memory allocators
I'm wondering why the following code does NOT work. 我想知道为什么以下代码不起作用。 The main idea behind it is as follows: 其背后的主要思想如下:
Clould you please tell me, why such inheritance does not work and how to fix it? 您能否告诉我,为什么这种继承无效,以及如何解决呢?
#include <boost/interprocess/managed_shared_memory.hpp>
#include <boost/interprocess/allocators/allocator.hpp>
#include <iostream>
using namespace boost::interprocess;
template <typename _Tp>
class MyStdAllocator : public std::allocator<_Tp>
{
};
template<class T, class SegmentManager>
class MyBoostAllocator : public allocator<T, SegmentManager>
{
};
typedef std::allocator<int> std_allocator;
typedef MyStdAllocator<int> my_std_allocator;
typedef allocator <int, managed_shared_memory::segment_manager> boost_allocator;
typedef MyBoostAllocator<int, managed_shared_memory::segment_manager> my_boost_allocator;
int main(int argc, char** argv) {
struct shm_remove {
shm_remove() {
shared_memory_object::remove("MySharedMemory");
}
~shm_remove() {
shared_memory_object::remove("MySharedMemory");
}
} remover;
managed_shared_memory segment(create_only,
"MySharedMemory", //segment name
65536);
//Create an allocator that allocates ints from the managed segment
allocator<int, managed_shared_memory::segment_manager>
allocator_instance(segment.get_segment_manager());
std_allocator *x1;
x1 = new std_allocator();
delete x1;
my_std_allocator *x2;
x2 = new my_std_allocator();
delete x2;
boost_allocator *y1;
y1 = new boost_allocator(segment.get_segment_manager());
delete y1;
// following lines generate compilation errors:
my_boost_allocator *y2;
y2 = new my_boost_allocator(segment.get_segment_manager());
delete y2;
std::cout<<"its working!\n";
return 0;
}
The compilation error is as follows: 编译错误如下:
../src/test.cpp:73:59: error: no matching function for call to ‘MyBoostAllocator<int, boost::interprocess::segment_manager<char, boost::interprocess::rbtree_best_fit<boost::interprocess::mutex_family>, boost::interprocess::iset_index> >::MyBoostAllocator(boost::interprocess::ipcdetail::basic_managed_memory_impl<char, boost::interprocess::rbtree_best_fit<boost::interprocess::mutex_family>, boost::interprocess::iset_index, 16ul>::segment_manager*)’
../src/test.cpp:73:59: note: candidates are:
../src/test.cpp:24:7: note: MyBoostAllocator<int, boost::interprocess::segment_manager<char, boost::interprocess::rbtree_best_fit<boost::interprocess::mutex_family>, boost::interprocess::iset_index> >::MyBoostAllocator()
../src/test.cpp:24:7: note: candidate expects 0 arguments, 1 provided
../src/test.cpp:24:7: note: MyBoostAllocator<int, boost::interprocess::segment_manager<char, boost::interprocess::rbtree_best_fit<boost::interprocess::mutex_family>, boost::interprocess::iset_index> >::MyBoostAllocator(const MyBoostAllocator<int, boost::interprocess::segment_manager<char, boost::interprocess::rbtree_best_fit<boost::interprocess::mutex_family>, boost::interprocess::iset_index> >&)
../src/test.cpp:24:7: note: no known conversion for argument 1 from ‘boost::interprocess::ipcdetail::basic_managed_memory_impl<char, boost::interprocess::rbtree_best_fit<boost::interprocess::mutex_family>, boost::interprocess::iset_index, 16ul>::segment_manager* {aka boost::interprocess::segment_manager<char, boost::interprocess::rbtree_best_fit<boost::interprocess::mutex_family>, boost::interprocess::iset_index>*}’ to ‘const MyBoostAllocator<int, boost::interprocess::segment_manager<char, boost::interprocess::rbtree_best_fit<boost::interprocess::mutex_family>, boost::interprocess::iset_index> >&’
make: *** [src/test.o] Error 1
This seems to be a "supported C++11" question. 这似乎是一个“受支持的C ++ 11”问题。 See 看到
http://wiki.apache.org/stdcxx/C++0xCompilerSupport http://wiki.apache.org/stdcxx/C++0xCompilerSupport
for which compilers support which features. 哪些编译器支持哪些功能。
Inheriting constructors is gnu4.8+ only. 继承构造函数仅适用于gnu4.8 +。
When they are you still have to explicitly put in a using construct. 当它们仍然存在时,您仍然必须显式地放入using构造。
template<class T, class SegmentManager>
class MyBoostAllocator : public allocator<T, SegmentManager>
{
public:
using allocator<T, SegmentManager >::allocator;
};
Until that is available, write the constructors in your derived class. 在可用之前,在派生类中编写构造函数。
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