Built-in Methods
Instance Method vs Static Method
Instance Methods (normal methods without declaring @) specifies with that particular declared instance. For ex. a unique event is specific to a specific calendar instance, and should not exist on other calendar instances.
Static Method doesn't care about any particular instance. For ex, a weekend on a calendar applies to all calendars since it is universally agreed upon how calendars work, regardless of instance
Also look into Class Method if need to consider inheritance.
class Calendar:
def __init__(self):
self.events = []
def add_event(self, event):
self.events.append(event)
@staticmethod
def is_weekend(dt):
passDataclasses
Without using Dataclass,
- If you print, it will be the memory address where the object resides.
- To print a string, will have to modify the _str_ dunder method
- A new object with identical information will be a new object
class Person:
def __init__(self, name, job, age):
self.name = name
self.job = job
self.age = age
person1 = Person("Geralt", "Witcher", 30)
person2 = Person("Yennefer", "Sorceress", 25)
person3 = Person("Yennefer", "Sorceress", 25)
print(id(person2))
print(id(person3))
print(person1)
print(person3 == person2)
"""
OUTPUT:
140244722433808
140244722433712
<__main__.Person object at 0x7f8d44dcbfd0>
False
"""With Dataclass:
- Print string information instead of object, unless using id()
- A new object will still be a new object, but if information is identical it will it will return True
- If forgot to write @dataclass...
- class variables instead of instance variables
from dataclasses import dataclass, field
@dataclass(order=True,frozen=False)
class Person:
sort_index: int = field(init=False, repr=False)
name: str
job: str
age: int
strength: int = 100
def __post_init__(self):
object.__setattr__(self, 'sort_index', self.strength)
def __str__(self):
return f'{self.name}, {self.job} ({self.age})'
person1 = Person("Geralt", "Witcher", 30, 99)
person2 = Person("Yennefer", "Sorceress", 25)
person3 = Person("Yennefer", "Sorceress", 25)
print(person1)
print(id(person2))
print(id(person3))
print(person3 == person2)
print(person1 > person2)
"""
Geralt, Witcher (30)
140120080908048
140120080907856
True
False
"""