changing only the operator in python code

Question

I have a piece of code that is repeating with only a math operator changing, i.e:

x1=a+b
x2=a-b
x3=a*b
x4=a/b

is there a way to write a function that receives the operator and only applies that and thus eliminate the need to write almost the same code many times?

hopefully, something like:

def operator_modularity(op):
    return a op b

operator_modularity(+)

Create a dictionary of operators from the [`operator`](https://docs.python.org/3/library/operator.html) module and pass the key. — Klaus D., Oct 26 '21 at 19:14
There is a standard `operator` module containing functions like `operator.add()`. Your code would be `op(a, b)` if passed one of these functions as `op`. — jasonharper, Oct 26 '21 at 19:15
Where do the `a` and `b` come from in `operator_modularity`? — d.b, Oct 26 '21 at 19:18
Check here https://stackoverflow.com/a/18591860/14310038 ...................................... ...... .... — Faika Majid, Oct 26 '21 at 19:25
d.b say they are constants for example UlisesBussi building a basic calculator but with modular code instead of the naive code duplication solution — GalSuchetzky, Oct 26 '21 at 19:28

score 3 · Answer 1 · edited Oct 26 '21 at 21:46

3

def operator_modularity(op):
    return eval(f"10 {op} 10")

operator_modularity("+")

edited Oct 26 '21 at 21:46

Dharman

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answered Oct 26 '21 at 19:26

takeyama

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eval is evil, it allows more than i want but it's a good direction tough, maybe combining it with the dictionary solution will give a safe and modular piece of code. – GalSuchetzky Oct 26 '21 at 19:30
lots of fun ahead! Yep, eval is evil: use for instance `op = " in [print('you have been hacked') for x in range(1)] #"` and have fun – Pac0 Oct 26 '21 at 21:41

score 2 · Answer 2 · answered Oct 26 '21 at 19:44

A great thing about Python is that you can keep pointers to methods. Another cool thing is the built in operators module that gives you method-call shaped references to said operators. So to do that, you could run the following:

def foo(a, b):
     operators_to_run = [operator.add, operator.sub, operator.mul]
     for op in operators_to_run:
         print(op(a,b))

There's no code repetition, and you get all the operators' results sequentially :) I hope that answers your question.

score 0 · Answer 3 · edited Oct 26 '21 at 19:25

0

I guess you could write some code like

def all_four_operations(num1, num2):
    return (num1 + num2, num1 - num2, num1 * num2, num1 / num2)

result_array = all_four_operations(1, 7)
x1 = result_array[0] # x1 = 8
x2 = result_array[1] # x2 = -6
x3 = result_array[2] # x3 = 7
x4 = result_array[3] # x4 = 0.14

edited Oct 26 '21 at 19:25

d.b

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answered Oct 26 '21 at 19:17

Jacob Glik

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10

You could probably do `return {"+": num1 + num2, "-": num1 - num2, "*": num1 * num2, "/": num1 / num2}` – d.b Oct 26 '21 at 19:25
this is still not preventing code duplication – GalSuchetzky Oct 26 '21 at 19:27

changing only the operator in python code

3 Answers3