Singleton Design Pattern - Advanced Python Tutorial #9

great video, i'm actually learning a from the design pattern videos

from abc import ABCMeta, abstractstaticmethod

class IPerson(metaclass=ABCMeta):
@abstractstaticmethod
def get_data():
"""Implement in child class"""

class SingletonPattern(IPerson):
__instance = None
def __new__(cls, *args, **kwargs) -> None: # new is already a static dunder method.
if not cls.__instance:
cls.__instance = super().__new__(cls)
return cls.__instance

def __init__(self, username):
# if not hasattr(self, "username"): prevents many instances
self.username = username
# else:
# raise Exception("This class is a singleton") notifies error

@staticmethod
def get_data():
print(f"Username: {SingletonPattern.__instance.username}")

if _name_ == "__main__":
person = SingletonPattern("Kevin").get_data()
person = SingletonPattern("John").get_data()

This is an overly-complex solution. Don't need any abstractions or classes. All you need is a global variable + 1 function.

Feels like you're writing Java in Python my dude.

nice one

Great video but you should be using 'is' and 'is not' for comparison against None.

lol, why using @staticmethod ? use @classmethod. or better implement _new_ ...

Python programmers almost never implement the Singleton Pattern as described in the Gang of Four book, whose Singleton class forbids normal instantiation and instead offers a class method that returns the singleton instance. Python is more elegant, and lets a class continue to support the normal syntax for instantiation while defining a custom __new__() method that returns the singleton instance. But an even more Pythonic approach, if your design forces you to offer global access to a singleton object, is to use The Global Object Pattern instead.

A Singleton pattern in python is a design pattern that allows you to create just one instance of a class, throughout the lifetime of a program. Using a singleton pattern has many benefits. A few of them are: To limit concurrent access to a shared resource.

Great explanation! I'm still trying to figure out where this pattern can be used. Anyway. Thanks!

why does he look like a 3d rendered model?

I think you should add thread lock. So it will make it thread safe

Thanks for sharing!

And what would be the point of this?

This solution, to some extent confuses singleton with static, unfortunately. A singleton object does not use static data and uses a factory for creation.

Can we inherit from this singleton class?

Why do we need, or do we need the IPerson class at all?

What was the need of an abstract base class?

This guy looks like Henry Cavill! Keep up the good work.

implementation using decorator

def singleton(cls):
instances = {}
def getinstance():
if cls not in instances:
instances[cls] = cls()
return instances[cls]
return getinstance

@singleton
class MyClass:
...

Cool tutorial! However, the get_instance and print_data should be class methods!

Great tutorial

These series is excellent, thanks!

u look like gta charector

Shouldnt this work without using Metaclass?

Can we make this pattern look more "pythonic" by overriding the _new_ static method instead of introducing get_instance?

there is a pythonic way for singleton

If you are noob in python ! Don't watch this

It’s great

Why do you need to create an interface for this singleton example??🤔🤔

Great explanation. Thanks

awesome !!!

Don't treat Python as Java. There are better ways to deal with the Singleton functionality.

thank you floren. need more video on the rest of the common design pattern.

make metaclass tutorial please

Hi bro . Help me I can't understand about this pattern topic can you explain pls? And how many types are there?

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please, continue)

I swear I learn more from you than from college

Hey! A very clear explanation as usual. A suggestion, you could display your video on the bottom left , that way it won't block any text.

Really you are the best bro!!!!!!!!!!👍👍👍

I was missing the explanation, on why you would do this? What are the applications? And why always use person as an example, which doesn't say anything. Couldn't you have used a more applied example? Other than that, I love your videos! Please keep up the good work!

Nice bro 👍👍

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