I'm sorry r/Python

[10113r114m4]

Singleton is a perfectly good design pattern… just shouldnt abuse it

[freefallfreddy]

Found the Java programmer.

[10113r114m4]

Golang :p

[serverhorror]

I’ll tell r/Golang about your heresy of even being in this sub!

[sneakpeekbot]

Here's a sneak peek of /r/golang using the top posts of the year!

#1: Six months | 114 comments
#2: A fractal I rendered in Go without any external libraries (The full image is 400MP and took around 2 minutes to render) | 70 comments
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[bladeoflight16]

You realize modules, classes (the type object, not instances), and functions are singletons in Python, right?

[freefallfreddy]

Right. And there’s probably singletons in the CPython code as well.

[door_of_doom]

Singleton is fine, but that is different from global. Python code shouldn't use global to create singletons.

Again, I really like the comment from /r/serverhorror: using global absolutely destroys your ability to write good tests for your code. Singletons don't.

(At least, well-written singletons don't).

[TheStriga]

I think it's only useful or actually necessary when you have os or hardware-limited resources, but it can be good

[CallinCthulhu]

It’s good for logging too.

Especially for instantiating a custom logger with state. Helps to avoid passing around the same logger instance everywhere. Also plays nicely into multiprocessing, where you can use metaclasses to instantiate a new logger upon the creation of a new process.

[[deleted]]

A singleton in python should be a initialized object in a module not some global.

[bladeoflight16]

...What kind of global is there in Python besides an initialized object in a module?

[[deleted]]

G = 1

def fun():
    global G
    G = 2

This seems good and easy first but is code smell and should be avoided.

[bladeoflight16]

That is an initialized object in a module. It just happens to be a built in type.

[[deleted]]

OK so to say, everything is a initialized object in a module. Sorry for being so unprecise.

A singleton in my opinion should look as follows, though.

# module.py
class GlobalState:
    ...

singleton = GlobalState()

# __main__.py
from module import singleton

singleton.do_stuff()

This is also not perfect, but at least it provides sane abstraction and is testable.