Iterable decorator

Question

I have a class in python with the following structure:

class MyClass:
    def __init__(self, iterable):
        self.iterable = iterable

    def example_0(self):
        for i in self.iterable:
            print(i)

    def example_1(self):
        for i in self.iterable:
            print(i + 1)

    def example_2(self):
        for i in self.iterable:
            print(i + 2)

That is, I have several methods that run different operations on an iterable that is an attribute of the class. I need to run for i in self.iterable for each method in the class, and I would otherwise like to use a decorator to all these methods, something like:

class MyClass:
    def __init__(self, iterable):
        self.iterable = iterable

    @iterate
    def example_0(self, i):
        print(i)

    @iterate
    def example_1(self, i):
        print(i + 1)

    @iterate
    def example_2(self, i):
        print(i + 2)

Can you help me write this decorator such that the behavior of my class is the same as the new class?

---

I tried this:

class MyClass:
    def __init__(self, iterable):
        self.iterable = iterable

    def iterate(self, f):
        def func(*args, **kwargs):
            for i in self.iterable:
                f(self, i, *args, **kwargs)
        return func

    @iterate
    def example_0(self, i):
        print(i)

    @iterate
    def example_1(self, i):
        print(i + 1)

    @iterate
    def example_2(self, i):
        print(i + 2)

and it returns: TypeError: iterate() missing 1 required positional argument: 'f'.

My main issue is I'm not sure how to put the decorator within my class, as it's iterating over an attribute of the class.

Answer 1

I don't think this has much advantage, but here's an option. This also allows for additional parameters.

from functools import wraps

def iterated(f):
    @wraps(f)
    def _f(self, *args, **kwargs):
        for i in self.iterable:
            f(self, i, *args, **kwargs)
    return _f

Example:

In [11]: class MyClass2:
    ...:     def __init__(self, iterable):
    ...:         self.iterable = iterable
    ...: 
    ...:     @iterated
    ...:     def example_0(self, i, k):
    ...:         print(i + k)

In [12]: MyClass2([1,2,3]).example_0(2)
3
4
5

This is to be defined outside the class. In your failing implementation, you forgot the self parameter in the returned closure.