C++: Template and Lambda

Question

Is it common to use something like the following in C++?

template <typename T> function<void(vector<T> &)> filter1 = [ ] (vector<T> &vec){
    int count = 0;
    for (T t : vec){
        if ( t.cost < 500 )
            vec.erase(vec.begin()+count);
        count++;
    }
};

template <typename T> void discount(float p, vector<T> &vec){
    filter1<T>(vec);
    int count = 0;
    for (T t : vec) {
        t.cost = t.cost - t.cost * p;
        vec.erase(vec.begin() + count);
        vec.emplace(vec.begin() + count, t);
        count++;
    }

btw I'm calling it tembda, cause its a mixture of Template and Lambda.

Answer 1

Is it common to use something like the following in C++?

No.

Firstly, std::function is a heavyweight abstraction which unnecessarily degrades the performance of your code in this case. Secondly, there's no advantage in using a lambda expression here over a simple template function - you are just going to confuse whoever reads your code.