How to replicate Ruby’s "each" method in Python?

Question

How can I make method each in Python like its in Ruby? Is that possible, am really do!

In Ruby its looks like:

%w[1 2 3 4].each { |i| puts i}

In Python we have for:

for i in [1, 2, 3]: print(i)

So, I want to make each method in Python, here is my code:

class Iter:
    def each(self, data):
        processed = data.__iter__()
        yield processed.__next__()


if __name__ == "__main__":
    test = Iter()
    print(list(test.each([1, 2, 3])))

Its working not as each, its return only first element. Thx in advance!

It only returns one element because you did yield processed.__next__() which only returns the first element of the iterator. Just return the iterator directly from each. list and most other constructs can use iterators since iterators are iterables like lists. — Carcigenicate
– Carcigenicate, Commented Dec 25, 2022 at 15:05
Also, you should really use iter and next instead of .__iter__ and .__next__ directly. In the end, this really just means that your each is an alias for __iter__. I would just properly implement the iterator interface instead of using Ruby conventions. The two don't appear to be equivalent anyway since Ruby's version takes a function/block/whatever they're called. — Carcigenicate
– Carcigenicate, Commented Dec 25, 2022 at 15:08
The reason you don't see this is a difference in philosophy. Ruby is an expression oriented language, so you can write a function (like each) that takes a block (which may be several lines long), and it looks very natural to call. Python's equivalent to Ruby's block is the lambda keyword, an anaemic one-line-only anonymous function. You can write each in Python (in fact, I have done so). But it's just not as useful in a language where blocks are limited to one line. — Silvio Mayolo
– Silvio Mayolo, Commented Dec 25, 2022 at 20:44

AlexK · Accepted Answer · 2022-12-26 01:37:00Z

1

class Iter:
    def each(self, data):
        yield from data

if __name__ == "__main__":
    test = Iter()
    for i in test.each([1, 2, 3]):
        print(i)

To implement the each method in python that is similar to Ruby, you can use the yield statement. If you use it inside a for it should work that way.

I'll also add the link to the documentation of yield statement here.

edited Dec 26, 2022 at 1:37

AlexK

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answered Dec 25, 2022 at 15:14

CodeNexus164

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2 Comments

SonyMag Over a year ago

Thx for your answer! But, can I do it without for ?

Carcigenicate Over a year ago

@SonyMag They're using for to replace the list call you were using. They have roughly the same purpose: to pull elements from the iterator.

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