应替换现有类型，添加新类型

我有一个基地std::vector和一个std::initializer_list<Attribute*>，它是由派生类组成的函数的参数Attribute class.

class Attribute {};
class Place : public Attribute {};
class Time : public Attribute {};
class Way: public Attribute {};

Place* place = new Place();
Time* time = new Time();
Way* way = new Way();
Place* place2 = new Place(...);
Time* time2 = new Time(...);

auto baseList = std::vector<Attribute*>({ place, time, way })

void updateBaseList(std::vector<Attribute*>& v, std::initializer_list<Attribute*> l);

What updateBaseList必须做的是，如果元素的类型l等于一baseList，更新该值baseList与其中之一l。如果没有遇到该类型baseList，它必须添加到它。

请注意，正在搜索的类型不是Attribute*，而是派生类。

我的尝试

void updateBaseList(std::vector<Attribute*>& v, std::initializer_list<Attribute*> l) {
    bool found;
    for (auto listIt = l.begin(); listIt != l.end(); ++listIt) {
        found = false;
        for (auto attrIt = baseList.begin(); attrIt != baseList.end(); ++attrIt) {
            if (typeid(**listIt) == typeid(**attrIt)) {
                *attrIt = *listIt;
                found = true;
                break;
            }
        }
        if (!found) {
            baseList.push_back(*listIt);
        }
    }
}

But the typeid(**listIt) and typeid(**attrIt)总是回来Base.

The goal

如果我打电话updateBaseList(baseList, { time2, place2 })基本列表应该是{ place2, time2, way }

您需要使类层次结构具有多态性。执行此操作的一个好方法是添加virtual ~Attribute() { }析构函数：

struct Attribute 
{
    virtual ~Attribute() { }
};

那么你的代码按预期工作 http://melpon.org/wandbox/permlink/FLTo8aQ4RRk5Y6pp:

{
    auto baseList = std::vector<Attribute*>({ place0, time0 });

    updateBaseList(baseList, {place2, time2, way0});
    assert(baseList[0] == place2);
    assert(baseList[1] == time2);
    assert(baseList[2] == way0);
    assert(baseList.size() == 3);

    updateBaseList(baseList, {place0});
    assert(baseList[0] == place0);
    assert(baseList[1] == time2);
    assert(baseList[2] == way0);
    assert(baseList.size() == 3);
}

不相关，但您可以实施baseList使用 C++11 range-for 循环更容易阅读：

void updateBaseList(std::vector<Attribute*>& v, std::initializer_list<Attribute*> l) 
{
    for (auto& litem : l) 
    {
        bool found = false;
        for (auto& attr : baseList) 
        {
            if (typeid(*litem) != typeid(*attr)) continue;

            attr = litem;
            found = true;
            break;
        }

        if (!found) 
        {
            v.push_back(litem);
        }
    }
}

您还可以利用标准算法来避免有状态的found多变的：

void updateBaseList(std::vector<Attribute*>& v, std::initializer_list<Attribute*> l) 
{
    for (auto& litem : l) 
    {
        const auto found = std::find_if(std::begin(v), std::end(v), [&](Attribute* p)
                                       {
                                           return typeid(*litem) == typeid(*p);
                                       });

        if (found == std::end(v)) 
        {
            v.push_back(litem);
        }
        else 
        {
            *found = litem;
        }
    }
}