A recursive function definition has one or more base cases, meaning input(s) for which the function produces a result trivially (without recurring), and one or more recursive cases, meaning input(s) for which the program recurs (calls itself). For example, the factorial function can be defined recursively by the equations 0! = 1 and, for all n > 0, n! = n(n − 1)!. Neither equation by itself constitutes a complete definition; the first is the base case, and the second is the recursive case. Because the base case breaks the chain of recursion, it is sometimes also called the "terminating case".

وقتی که حتی روی یه فانکشن ساده هم دیباگر میزنی تا بفهمی داره توی call stack چه غلطی میکنه

recursive binary search implementation :

def binary_search_recv(list, number , low , high):
   if low > high:
      return -1

   mid = (low + high)
   guess = list[mid]

   if guess == number:
      return mid

   if guess > number:
      return binary_search_recv(list , number , low , mid - 1)
   else:
      return binary_search_recv(list, number , mid + 1 , high)

note:
_ with every recall using return with their function will cause re-run the function with their provided (args)
_ in the recall method the state of the variables must have to be passed because of reruring the function proccess

Factory Implementation

from abc import ABC, abstractmethod


class FormatNotFound(Exception):
    pass

class File(ABC):
    def __init__(self, file):
        self.file = file

    @abstractmethod
    def make(self):
        pass

    def call_edit(self):
        product = self.make()
        result = product.edit(self.file)
        return result


class JsonFile(File):
    def make(self):
        return Json()


class XmlFile(File):
    def make(self):
        return Xml()


class Json:
    def edit(self, file):
        return f'working on {file}.json'


class Xml:
    def edit(self, file):
        return f'working on {file}.xml'


def client(file, format):
    try:

        formats = {
        'json': JsonFile
        , 'xml': XmlFile
    }
        result = formats[format](file)
        return result.call_edit()
    except KeyError:
        raise FormatNotFound



if __name__ == '__main__':
    print(client('test', 'json'))

factory has 3 component :
1. Creator
2. Product
3. Client

for the golang programming language composition over inheritance is consider the most important basic part

A struct is C's and C++'s notion of a composite type, a datatype that composes a fixed set of labeled fields or members. It is so called because of the struct keyword used in declaring them, which is short for structure or, more precisely, user-defined data structure.