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.
>Solution :
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.