标签: boost-any

以下代码是否安全？

boost::any any_value;

{
    std::string s = "HelloWorld";
    any_value = s;
}

std::string ss = any_cast<std::string>(any_value);

我希望摆脱对我的代码的boost依赖.我有以下结构构造.在代码中的另一个地方调用和使用此结构时boost::any_cast.我知道模板类会这样做,但发现很难写这个模板. - C++新秀.

 struct Properties {
 public:
 Properties() {}
 Properties(const std::string &s, const boost::any & p) {
      name = s;
      value = p;
 }

 template <typename T>
 Properties(T n) {
      value = n;
 }
 boost::any value;

 std::string name;
};

我想通过索引获得可变参数模板中的类型.索引被指定为模板参数.我设法找到一个有效的'hack',但我相信它不符合可变参数模板编程的精神.此外,它使用额外的内存.

这是代码和一些解释:

template <typename... InputPortTypes>
class PipelineReceiver
{

protected:

    // This tuple is used for storing types only
    // Hence, I would like to get rid of it, but I am not sure how.
    std::tuple<
    std::function<std::unique_ptr<InputPortTypes> (int)>...
    > InputPortsTuple;

    // This vector is used for storing the actual objects
    // This is needed to be able to access/change its elements
    // during run time later on.
    // The vector is used for storage of function pointers (i.e. of type std::function) …

在尝试boost::any通过boost::any_cast引用转换检索实例后，我无法保持常量正确性。

我的代码：

MyMap paramMapToSet;
MyMap& paramMap = &paramMapToSet;
const MyMap& constParamMap = &paramMapToSet;

A hoe;
paramMap.set(hoe, "structA");

// this works
A& hoeRef = paramMap.getByRef<A>("structA");
hoeRef.myInt = 101;
cout << paramMap.get<A>("structA").myInt << endl; // prints 101

// as well as this:
hoe = constParamMap.get<A>("structA");
cout << hoe.myInt << endl;

// and this:
const A& constHoeRef = paramMap.getByRef<A>("structA");
cout << constHoeRef.myInt << endl;

// however this doesn't work, why?? (error message below)
const A& constHoeRef = constParamMap.getByRef<A>("structA");
cout …

Boost <boost/any.hpp>有:

template<typename ValueType>
ValueType any_cast(any & operand);

template<typename ValueType>
inline ValueType any_cast(const any & operand);

(以及其他变体.)这种组合不应该导致诸如boost::any_cast<int>(my_any);？之类的调用模糊不清吗？

我问,因为如果我写这个程序:

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

template<typename ValueType>
ValueType any_cast(boost::any & operand)
{
        return boost::any_cast<ValueType>(operand);
}

int main()
{
        int x = 123;
        boost::any my_any(x);
        std::cout << "my_any = " << any_cast<int>(my_any) << "\n";
        return 0;
}

我确实抱怨模糊不清:

g++ -std=c++14 -O3 -Wall -pedantic -pthread main.cpp && ./a.out
main.cpp: In function 'int main()':
main.cpp:14:57: error: call of overloaded 'any_cast(boost::any&)' is …

我有一个很多boost :: any的向量在这个向量中我需要对std :: vector和IContainer类型的元素执行一些操作

class   IContainer
{
public:
  virtual ~IContainer(){}
  virtual const boost::any operator[](std::string) const = 0;
};

class   AContainer : public IContainer
{
  std::vector<int>      vect_;
  std::string name_;
public:
  AContainer() : vect_({0, 1, 2, 3, 4, 5}), name_("AContainer") {}
  virtual const boost::any operator[](std::string key) const
  {
    if (key == "str")
      return (name_);
    if (key == "vect")
      return (vect_);
    return nullptr;
  }
};

所以我做了以下功能(非常丑陋),但谁工作正常

我是 const std::vector<boost::any>&

for (const auto & elem : m)
    {
      try
        {
          std::vector<int> v = …