[英]Initialize a vector of shared pointers in varidic data structures
I'm playing with variadic structures, and I'm like a kid with a box of matches. 我在玩可变的结构,就像一个拿着火柴盒的孩子。 The goal is to initialize a vector of base class pointers using parameter pack expansion. 目标是使用参数包扩展来初始化基类指针的向量。 Given: 鉴于:
struct base {
base() {};
virtual ~base() {};
...
};
template<class T>
struct derived : public base {
derived() {};
virtual ~derived() {};
...
};
struct collection {
collection()
: a{ make_shared<derived<int>>(),
make_shared<derived<float>>(),
make_shared<derived<double>>() } {};
~collection() {};
vector<shared_ptr<base>> a;
...
};
Is it possible to set the items in the vector using pack expansion? 是否可以使用包扩展设置矢量中的项目? The following doesn't compile, but you get the idea. 以下内容无法编译,但是您可以理解。 Argument lists would also be nice. 参数列表也很好。
template<class ...t>
struct collection2 {
collection2() : a{ make_shared<derived<t>>... } {}; //????
~collection2() {};
vector<shared_ptr<base>> a;
};
So you should be able to declare it like this: 因此,您应该可以这样声明它:
int main() {
collection2<int,float,double> a;
return 0;
}
Anyway thanks for your input or suggestions to alternatives. 无论如何,感谢您的输入或其他建议。
Your attempt is almost right. 您的尝试几乎是正确的。 You're just missing ()
to call make_shared
: 您只是缺少()
来调用make_shared
:
template<class ...t>
struct collection2 {
collection2() : a{ make_shared<derived<t>>()... } {};
~collection2() {};
vector<shared_ptr<base>> a;
};
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