如何make_shared派生类? [英] How to make_shared a derived class?

问题描述

我想对派生类使用make_shared<T>函数，如下所示

I want to use the make_shared<T> function with a derived class, like below

class Base {
     public:
     typedef std::shared_ptr<Base> Ptr;
};

class Derived : public Base {};

Base::Ptr myPtr = std::make_shared(/* Derived() */ );

如何告诉make_shared构建这样的对象?

How can I tell make_shared to build such an object?

我想避免经典

Base::Ptr ptr = Base::Ptr(new Derived());

要在make_shared函数中使用单个alloc.

To make use of the single alloc in the make_shared function.

推荐答案

std::shared_ptr具有可以从shared_ptr<Derived>生成shared_ptr<Base>的转换构造函数，因此以下应该起作用:

std::shared_ptr has a converting constructor that can make a shared_ptr<Base> from a shared_ptr<Derived>, so the following should work:

#include <memory>
class Base {
    public:
    typedef std::shared_ptr<Base> Ptr;
};
class Derived : public Base {};

int main() {
    Base::Ptr myPtr = std::make_shared<Derived>();
}

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