[英]Using unique_ptr and vector
I have this code: 我有以下代码:
v8::Handle<v8::Value> StartMethod(const v8::Arguments &args) {
v8::HandleScope scope; // node_isolate
int length = args.Length();
std::vector<std::unique_ptr<char[]>> argv;
for(int i=0;i<length;++i) {
if(args[i]->IsString()) {
v8::String::Utf8Value str(args[i]);
const int strLen = ToCStringLen(str);
if(strLen) {
std::unique_ptr<char []> data(new char[strLen+1]);
strcpy_s(data.get(), strLen+1, ToCString(str));
argv.push_back(std::move(data));
}
}
}
return scope.Close(v8::Int32::New(MainMethod(argv.size(), &(argv[0]._Myptr))));
}
I am using std::move
and it is working fine. 我正在使用
std::move
,并且工作正常。 When i do not use std::move it gives me compiler errors because of unavailability of assignment
function. 当我不使用std :: move时,由于
assignment
函数不可用,它给了我编译器错误。
But Does it guarantees that when vector changes its location, may be because of some internal re sizing and move objects around, nothing bad would happen ? 但是,它是否可以保证当向量改变其位置时,可能是由于某些内部调整大小并移动对象而不会发生任何不良情况?
vector<T>::push_back
gives the strong exception safety guarantee for move-only types if and only if the move construtor of T
does not throw . 当且仅当
T
的移动构造函数未抛出时, vector<T>::push_back
为仅移动类型提供强大的异常安全保证。
In your case T
is a unique_ptr
for array objects, whose move constructor is declared noexcept
(§20.7.1.3), so you are indeed fine here: If the internal resizing of the vector throws a bad_alloc
, the vector will remain unchanged and usable. 在您的情况下,
T
是数组对象的unique_ptr
,其移动构造函数声明为noexcept
(第2.0.7.1.3节),因此,您的确不错:如果向量的内部调整大小抛出bad_alloc
,则向量将保持不变且可用。
I am not sure if I got your question right, but under the assumption that std::vector doesn't have any unexpected behaviour, yes, it is garantueed. 我不确定我是否正确回答了您的问题,但是在std :: vector没有任何意外行为的假设下,是的,它是可靠的。 By executing
std::move()
you transfer the control over the underlaying pointer to the std::unique_ptr
in the std::vector
. 通过执行
std::move()
您可以将对底层指针的控制权转移到std::vector
的std::unique_ptr
。 From this point on it should behave like a std::vector<char*>
从这一点来看,它的行为应类似于
std::vector<char*>
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