如何声明一个unique_ptr的向量作为类数据成员？ [英] How to declare a vector of unique_ptr's as class data member?

问题描述

我想有一个unique_ptr的向量作为我正在做的类的成员。

I'd like to have a vector of unique_ptr's as a member of a class I'm making.

class Foo {
    [...]

private:
    vector<unique_ptr<Bar>> barList;
}

但是我开始从 VS2010 编译器：

But then I start getting cryptic error messages from the VS2010 compiler:

error C2248: 'std::unique_ptr<_Ty>::operator =' : cannot access private member declared in class 'std::unique_ptr<_Ty>'

D转到Microsoft的实现 std :: _ Copy_impl<> ...

Along with a handful of error lines below that which dive into Microsoft's implementation of std::_Copy_impl<>...

我将成员声明更改为

vector<unique_ptr<Bar>>* barList;

并编译。但我不禁想知道为什么我不能这样我最初想要的方式？对于咧嘴，我尝试这个，它工作正常：

And it compiles. But I can't help but wonder why I can't do it the way I originally wanted? For grins, I tried this and it works fine:

vector<Bar> barList;

但现在我失去了 unique_ptr 。我想要我的蛋糕，我也想吃它！

But now I lose the convenience of unique_ptr. I want my cake and I want to eat it too!

推荐答案

这里的问题是， Foo 的复制赋值操作符。

The problem here is that somewhere, your code is attempting to call the "copy-assignment" operator of Foo.

这会导致编译器尝试生成副本运算符，它调用 Foo 的所有子对象的复制赋值运算符。最终，这会导致尝试复制 unique_ptr ，这是不可能的操作。

This causes the compiler to attempt to generate a copy-assignment operator which calls the copy-assignment operators of all the subobjects of Foo. Eventually, this leads to an attempt to copy a unique_ptr, an operation which is not possible.

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