there typically tends to be in Python, some correspondence between some top level syntax or function and some underscore method that implements that syntax or function
~James Powell
James Powell: So you want to be a Python expert? | PyData Seattle 2017
Example to show the above concept
class Some:
def __init__(self):
self.items = [1,2,3,4]
def __call__(self):
print('hello there')
def __equal__(self, other):
return self.items == other.items
def __getitem__(self, index):
return self.items[index]
some = Some()relations between dunder (double underscore) methods and top level syntax:
__call__->some()__equal__->some == other__getitem__->some[4],list(some)...
Creating a singleton in Python
Modules are imported only once, everything else is overthinking. Don't use singletons and try not to use globals.
Why are Python's 'private' methods not actually private?
When I first came from Java to Python I hated this. It scared me to death.
Today it might just be the one thing I love most about Python.
Remember, encapsulation is not even weakly related to "security", or keeping the kids off the lawn. It is just another pattern that should be used to make a code base easier to understand.
What's the pythonic way to use getters and setters?
The "Pythonic" way is not to use "getters" and "setters", but to use plain attributes(...)
If later, you want to modify the setting and getting, you can do so without having to alter user code, by using the property decorator
Why is init() always called after new()?
Use __new__ when you need to control the creation of a new instance.
Use __init__ when you need to control initialization of a new instance.
__new__ is the first step of instance creation. It's called first, and is responsible for returning a new instance of your class.
In contrast, __init__ doesn't return anything; it's only responsible for initializing the instance after it's been created.
In general, you shouldn't need to override __new__ unless you're subclassing an immutable type like str, int, unicode or tuple.
~From April 2008 post: When to use new vs. init? on mail.python.org.
Al Sweigart: The Amazing Mutable, Immutable Tuple
Everyone knows Python tuples are immutable, but an immutable tuple that contains mutable objects is itself mutable. Or is it?