How can one achieve generics in python? Something like Java or C++ offers

Question

I'm working with generics in python, and want to know if I can achieve generics in python as other languages. The syntax needs not to be same as other languages but if I can do something like


template<typename T>
class List {
public:
    T array[10];
};

int main() {
    List<int> list;
}

I tried the below code but I'm not sure how can I achieve the same as C++ or Java. Like, I shouldn't be allowed to add objects of any other type once I define the data type on initialization.


from typing import TypeVar, Generic, List

T = TypeVar('T')


class CircularQueue(Generic[T]):

    def __init__(self):
        self._front = 0
        self._rear = 0
        self._array = list()

    def mod(self, x): return (x+1) % (len(self._array)+1)

    @property
    def is_full(self):
        return self.mod(self._rear) == self.mod(self._front) + 1

    def insert(self, element: T):
        if not self.is_full:
            self._rear += 1
            self._array.append(element)


if __name__ == "__main__":
    # I want to Initialize the queue as cQueue = CircularQueue<int>()
    # Something that other compiled languauges offer
    # Is it possible to do so?
    # Or any other method so that I can restrict the type of objects.
    cQueue = CircularQueue()
    cQueue.insert(10)

    # Here I want to raise an error if I insert any other type of Object
    cQueue.insert('A')

I think numpy might do things like this, you could check out how it works — Barmar, Jul 11 '19 at 20:12
But in general, languages like Python are not designed around declaring strict types. — Barmar, Jul 11 '19 at 20:12
Nice question, but I don't think it's possible in Python, due to it's typing system. [This somewhat related question](https://stackoverflow.com/questions/11328920/is-python-strongly-typed) might help you better understand typing in Python. — gmauch, Jul 11 '19 at 20:14
Python pretty much uses "duck typing", which means in practice, it's mostly generic by default. — jjramsey, Jul 11 '19 at 20:15

score 3 · Accepted Answer · answered Jul 11 '19 at 20:16

Python does not have the notion of generics but one could say that every function is generic because parameters are not actually typed. This is a duck typing approach where anything that walks like a duck and quacks like a duck it treated as a duck. So, typically, "generic" functions would only check if the parameters or objects have the minimal set of required attributes and process the data accordingly.

How can one achieve generics in python? Something like Java or C++ offers

1 Answers1