I have a very basic question about why I need __init__ in declaring a class in Python.

For example, in this link, an example was introduced

class Person:
  def __init__(self, name, age):
    self.name = name
    self.age = age

p1 = Person("John", 36)

print(p1.name)
print(p1.age) 

But the above example requires a series of arguments as ("John", 36). When the number of arguments is large, they may be error-prone in the input. I can use *args, but it also requires the order of argument. If I just provide a default value of the name and age, and modify in need, will it simplify the practice? For example

class Person:
  def __init__(self, name, age):
    self.name = name
    self.age = age
    
class Person2:
  name = "John"
  age = 36    
  
class Person3:
  def __init__(self, *args):
    self.name = args[0]
    self.age = args[1]
      

p1 = Person("John", 36)
print(p1.name)
print(p1.age)

p2 = Person2()
print(p2.name)
print(p2.age)


p2.name = "Mike"
p2.age = 35
print(p2.name)
print(p2.age)


p3 = Person3("John", 36)
print(p3.name)
print(p3.age)

Person2 is perhaps the simplest. But, will Person2 be a good practice?

CodePudding user response：

You may want to read into the difference of class and an instance of a class: Person2 will not fly as every person would be the same. You use the class here basically as a namespace without further usage.

Person3 is basically a bad version of Person1.

Person1 will be ok and not error prone as you can also pass the arguments as keyword arguments (Person(name=..., age=...).

You may also have a look at dataclasses as they remove this kind of boilerplate: https://docs.python.org/3/library/dataclasses.html