this post was submitted on 01 Jul 2023
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Python 2 in Python 3! (programming.dev)
submitted 1 year ago* (last edited 1 year ago) by qwop@programming.dev to c/python@programming.dev
 

A post about how this community's banner used the python 2 print syntax - print "Hello World" - made me question, can we print a hello world message in Python 3 without using parentheses?

It turned out to be sort of a fun challenge, I've found 3 different approaches that work. I'd be interested to see what you come up with! (it seems I can't put spoilers in Lemmy, so I won't share my solutions yet in case y'all want to have a go).

Edit: Posted my solutions in the comments

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[โ€“] qwop@programming.dev 7 points 1 year ago (1 children)

Alright, here are my solutions :)

  1. Import Easter egg
import __hello__

Not the most technically interesting, but a fun Easter egg!

  1. Class decorators
@print
@lambda _: "Hello World"
class Foo: 
    ...

Decorators are another way of calling a function, so can be abused to solve this task. You need to decorate a class rather than a function though, since a function definition requires parentheses!

  1. Dunder methods
class Printer:
    __class_getitem__ = print

Printer["Hello World"]

There might be some other Dunder methods you can use to do this, although it's sort of difficult since most (e.g. __add__) only describe behaviour on the instance of the class.

  1. More dunder methods
from _sitebuiltins import Quitter
Quitter.__add__ = print
exit + "Hello World"

Writing number 3 made me realise I just needed to find a class that already had an instance and change that. I'm sure there are many other cases of this, but here's one!

[โ€“] McCheng@lemmy.fmhy.ml 1 points 1 year ago

Very interesting solutions. I was in the direction of using dunder methods but could not figure out how. Haven't heard of the __class_getitem__. The second solution is especially inspiring.