boost circular_buffer holdingポインタ

Question

循環バッファに上書きされる前にオブジェクトが削除されるのを防ぐ方法はありますか？ここに私の質問を説明するいくつかのコードです。

boost::circular_buffer<MyObject*> cBuf(5); 
cBuf.push_back(new MyObject()); // cBuf[0] 
cBuf.push_back(new MyObject()); // cBuf[1] 
cBuf.push_back(new MyObject()); // cBuf[2] 
cBuf.push_back(new MyObject()); // cBuf[3] 
cBuf.push_back(new MyObject()); // cBuf[4] 

// before this overwrite occurs, how do i make sure the pointer 
// position cBuf[0] is deleted? 
cBuf.push_back(new MyObject()); // this will overwrite position 0 

Answer 1

これはスマートポインタの古典的なシナリオです。任意のスマートポインタ。

最も簡単な選択ははstdされるだろう

:: unique_ptrを：

Live On Coliru

#include <boost/circular_buffer.hpp> 
#include <iostream> 

struct MyObject { 
    MyObject(int i) : _i(i) { std::cout << __FUNCTION__ << " _i=" << _i << "\n"; } 
    ~MyObject()    { std::cout << __FUNCTION__ << " _i=" << _i << "\n"; } 
    int _i; 
}; 

int main() { 
    using Ptr = std::unique_ptr<MyObject>; 
    boost::circular_buffer<Ptr> cBuf(5); 
    cBuf.push_back(std::make_unique<MyObject>(0)); // cBuf[0] 
    cBuf.push_back(std::make_unique<MyObject>(1)); // cBuf[1] 
    cBuf.push_back(std::make_unique<MyObject>(2)); // cBuf[2] 
    cBuf.push_back(std::make_unique<MyObject>(3)); // cBuf[3] 
    cBuf.push_back(std::make_unique<MyObject>(4)); // cBuf[4] 

    std::cout << "Full, pushing extra\n"; 

    cBuf.push_back(std::make_unique<MyObject>(5)); // this will overwrite position 0 

    std::cout << "Done\n"; 
} 

プリント：

MyObject::MyObject _i=0 
MyObject::MyObject _i=1 
MyObject::MyObject _i=2 
MyObject::MyObject _i=3 
MyObject::MyObject _i=4 
Full, pushing extra 
MyObject::MyObject _i=5 
MyObject::~MyObject _i=0 
Done 
MyObject::~MyObject _i=1 
MyObject::~MyObject _i=2 
MyObject::~MyObject _i=3 
MyObject::~MyObject _i=4 
MyObject::~MyObject _i=5