What is the type of a vector that stores a vector of one function and one vector of std::string-CodePudding

I am trying to figure a thing out right now and I can't, I need to find a type for this

(python)

def fn1(hello: list[str]) -> None:
    pass

mv = [(fn1, ("1", "hello", "12", "no")), (fn1, ("w", "ufewef", "1ee", "no"))]  # any size

what is a C type for mv? (doesn't matter if it's mutable or not)

I tried std::vector<std::vector<std::string, std::function>> but it kelp throwing an error, is there a way to do it or will have to use two vectors?

CodePudding user response：

These types get complicated, so to make them shorter I'll first define a couple of type alias:

using StringVec = std::vector<std::string>;
using StringVecFunc = std::function<void(const StringVec&)>;

Now the type of your data container could be any of these:

using T1 = std::vector<std::tuple<StringVecFunc, StringVec>>;

using T2 = std::vector<std::pair<StringVecFunc, StringVec>>;

struct StringVecFuncAndArgs {
    StringVecFunc func;
    StringVec args;
};
using T3 = std::vector<StringVecFuncAndArgs>;

The big difference is how you access elements of the thing holding one function and one string-container (like the python tuples). For std::tuple you use std::get<0>(t) and std::get<1>(t) or std::get<StringVecFunc>(t) and std::get<StringVec>(t). For std::pair you use p.first and p.second. For the custom struct you use data.func and data.args.

The tuple solution is maybe the most direct translation from the idea of a Python tuple. The pair is quick and easy if it doesn't need to be used from a lot of code. The custom struct solution takes the most work, but lets you give helpful names to the members.

CodePudding user response：

My program uses a stringVec struct that declares a vector<string> hello and a function that returns void stringVecFunc, which to use as an example prints the values of hello.

struct stringVec {
    vector<string> hello;
    void stringVecFunc();
};

void stringVec::stringVecFunc() {
    for (auto &x: hello) cout << x << "\t";
    cout << endl;
}

After this, a vector is responsible for storing data of type stringVec by this way:

stringVec stringVec1;
stringVec1.hello = {"hi", "hello", "hi", "hello"};

vector<stringVec> vec;

you can run a complete example here