CODEWITHSUNDEEP
python
IgorRogachov
IgorRogachov

Reputation: 61

Write a function to calculate the sum of numbers in python, which is called many times as sum (1) (2) (3)

You need to write a function on python that is called an indefinite number of times, each time it takes a number and returns their sum, for example sum (1) (2) (3) == 6. I found the code for javascript, but I did not find how to redefine it in python __str __ method for the function. How can I override a method or is there another solution?

The code I tried to write:

def sum(n):
    total = n
    def f(k):
        nonlocal total
        total += k
        # f.__str__ = lambda : print(total) # no
        return f
    return f

print(sum(1)(2)(3))

This is working javascript code:

function sum(a) {

  let currentSum = a;

  function f(b) {
    currentSum += b;
    return f;
  }

  f.toString = function() {
    return currentSum;
  };

  return f;
}

alert( sum(1)(2) ); // 3
alert( sum(5)(-1)(2) ); // 6
alert( sum(6)(-1)(-2)(-3) ); // 0
alert( sum(0)(1)(2)(3)(4)(5) ); // 15

Upvotes: 0

Views: 2430

Answers (3)

Alexey Kislitsin
Alexey Kislitsin

Reputation: 806

What about this:

def summ(a):
    current_sum = a

    return lambda x: current_sum + x

print(summ(1)(2))
>>>3

Upvotes: 0

Sunitha
Sunitha

Reputation: 12015

It is better to use a class instead of an inner function, and return an object of that class. You would then be able to use the magic __call__ method again and again, if you make it return the same object.

def sum(n):
    class Sum(object): 
        def __init__(self, k):
            self.total = k

        def __call__(self, k):
            self.total += k
            return self

        def __str__(self):
            return str(self.total)

        def __repr__(self):
            return str(self)

    return Sum(n)

Output

>>> sum(1)
1
>>> sum(1)(2)
3
>>> sum(1)(2)(3)
6

Upvotes: 1

Messypuddle
Messypuddle

Reputation: 429

If the function is going to be used as func(a)(b)(c)(d)(...) why not just use func([a,b,c,d,...]) ? In this case:

sum([a,b,c,d])

Upvotes: 0

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