Class Methods, Static Methods, & Instance Methods EXPLAINED in Python
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- Опубликовано: 20 дек 2022
- Don't you ever go to sleep at night wondering what a static method is, or what a class method is, or even what both are and how they are used in Python? Well now you don't have to worry about those hours of insomnia, because in this lesson we'll be covering all of that!
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I have been learning so much from your videos! Your presentation of the material is superb. Keep up the great work!
It took ages for me to understand this. I never came across with such clear explanation. Thank you. Thank you so much.
Great content again. Really helpful for getting to grips with OOP in python
Interessantissimo video Federico, sono principiante nel mondo della programmazione, quindi i tuoi video hanno reso più facile la comprensione di molti concetti, continua così!
everytime I watch one of your videos they are always explained really well, thanks I appreciate it a lot
Thank you so much, finally I got the concept!
Your thumbnail stands out so much, keep up your style man!
Thanks you made it really clear about the class method
Thank you so much for clearly explaining the difference between @classmethod and @staticmethod with an example.
This really helped me to understand the usage of @classmethod.
I think you would have been better served by introducing the idea of scope in this discussion. Also, I always think the best way to introduce the topic of the class method is by introducing a class variable like an instance counter that increments/decrements when a new instance of the class is created. Also, it wouldn’t hurt to put print statements in your constructors just to illustrate when they are called and how they affect class vars.
Great stuff. Hardly any tutorial explains these.
the @staticmethod is NOT optional. Simply removing the self keyword does NOT make it a static method, and will have weird results.
Correct, what I said regarding that was a mistake on my part in the video.
Thanks
@staticmethod is optional. always like that in Python. proof just run this snippet below it works fine. please dont confuse the content creator by making misleading statement as this Indently's gentleman making this content who I admire is still apparently learning Python too maybe he just read python doc once and then decided making Python videos. it needs to come from experiences. I stand corrected that the use of staticmethod decorator is OPTIONAL. All come with good intentions. hope this helps. The example code to prove it below:
class Calculator:
def __init__(self, version: int) -> None:
self.version = version
def no_static_decorator(text: str, *lucky_no: int) -> None:
print(f'{text} and the luck number is {sum(lucky_no)}')
Calculator.no_static_decorator("it works", 4, 9)
Hej @@tomjones8293, actually @staticmethod is NOT optional. Static methods van be called through class name as you did. But they can be called through instance too. Try that and you'll see that without decorator Python tries to pass instance reference as a first parametr.
Awesome video! Thank you. I have never thought of it but is this the only way to override a constructor in python?
Great explanation. Thank you ☺
Please don't stop making these. These videos are very useful and really enjoyable to watch!
awesomely explained. well done
very clear, easy to understand
This clears up these concepts!
First of all I really appreciate your content.
You are doing a great job.
Regarding class methods and using it for constructing class instances, I'd rather use just static methods.
Class methods are usually used for meta programing which is a way more advanced topic (which you rarely actually use)
Great explanation!!
Thanks, that's a nice guide! I wonder what editor you are using in the video, with what extensions?
Pycharm, new ui
Thumbs up! great video thanks
Is that PyCharm? Because mine looks different
Edit: Its in the settings its called New UI
You could have added that... class methods can refer to and modify class variables. These variables are shared between the class and all instances of the class. Also, static methods... you showed can be used relative to the class - as in classname.static_method(). But, you can also use them relative to an instance of the class - as in federico.age_from_year().
modifying a class attribute is kinda weird...expect maybe a counter or something like that.
Wow what a good presentation. My appreciation!
Glad you liked it!
great video! I'm new to coding and have just begun learning Python. I'm currently using VSCode. Which editor are you using? It looks clean with only your code and the terminal visible.
PyCharm Community Edition
Thankyou so much sir
@4:08, I don't think so it will be perfectly fine unless we give a static method decorator for that.
thank u.. but i wanna know the name of this ide that ur using
I like ur performance :) # thumb up
good keep it up
What font are you using? I like that '->' looks like an arrow without a break
Pycharm, with the setting that does that enabled
Good video
Good
if i have a python class of 1000 dogs and it all works as a class should, how do i search the dog class using a 'string' for a particular dog- say 'beagle' - I want to use a string because I am iterating through a large python list(which is strings) I can't figure out how to do it?
ibreed in self.dogs
self.dogs.index(breed)
I'd do:
def __iter__(self):
for breed in self.dogs:
yield breed
def __ contains__(self, breed):
return breed in list(self)
actually, if it's a list, I'd subclass list:
class DogList(list):
...
thought py3 has a new library that helps with this, though I haven't used it, and I forgot the protocol..but never be afraid to subclass builtins.
can we access static method by using object reference?
Yes you can but can't access the instance property (variable) so it's similar to using the normal function
I hope not to be wrong but there is a small error
You said the addition of @staticmethod was a choice. If you remove self tho, it's not a choice anymore
This is because python automatically sends the self argument when the function is called (in that case self will end up between the numbers) so the decorator is needed
I'm not trying to be rude and I'm not sure I am right, so correct me if I am not
You're not wrong, I made a mistake when I was recording as pointed out from several comments :)
def method(*args):
would work in either case.
sublime
Hey listen I want a brief lecture on class and class function
a class is a dictionary of variables and functions. There are no class functions. It's class method, instance method, static method.
Note: see that __main part
One tiny unrelated fix - Your "age_from_year" function actually needs the exact date of birth, to determine your age, so it can check whether current date is before or after your birthday. If you only enter 1997, and now we are in 2023, running your code today returns an age of 26, but if your birthday is in August, and today we're in February, you are still 25.
ok but this is demo code, to show static - class difference, the real code would also react to leap year.
Actually WTF is the answer! OOP in Python is a mess!
why?
@@DrDeuteron Just look at it. It's all implemented really weirdly. I don't know a single language that has as weird OOP as Python...
@@fairphoneuser9009 I think it makes perfect sense. Do you ever call super or use meta classes?
I use classmethods all the time, esp. as constructor helpers...since I never do work in __init__, that method is for setting instance attributes, and that is it. If I need to, say make the instance from a file...I am not reading a file in init, rather:
@classmethod
def fromfile(cls, filename):
with open(filename, 'r') as fsrc:
return cls(*some_function(fsrc.readlines())
and I get a new instance with the file data loaded.
For static methods, say I have a class whose attributes are different real time series, well if I want an fft or something:
@staticmethod
def rfft(x_i):
return np.fft.rfff(x_i)
the reason I put it in class is that I want the object to be able to do everything that needs to be done to it to be part of the interface. I don't want a user looking for np.ftt.rftt and doing it themselves, or making the mistake of using a full fft for complex inputs. A class should contain ALL the functions you would want to use on it,,,even if they don't depend on instance/class attributes.