instancemethod, classmethod, staticmethod

• Class

- Steps

1. Create class

2. Create three instance methods within the class

     - Initiator method, asigned value argument to value object.

     - increment method, change value object attribute

     - decrement method, change value object attribute

3. Create instance

4. Call instance methods

 

POINT : Must create instance first, call it then.

1. 
class Counter():

2.
    def __init__(self, value=0): 
        self.value=value 
    def increment(self, delta=1): 
        self.value+=delta 
    def decrement(self, delta=1): 
        self.value-=delta
3.        
counter=Counter()

4.
counter.value
>>>0

counter.increment(3)
>>>3

counter.decrement(2)
>>>
1

 

• classmethod

- Steps

1. Define class

2. Define one instance method and two classmethods 

    - One instance method : Initiator method, asigned email, password argument to email, password object.

    - Two classmethods : Declare classmethod fromTuple using with decorator@, first argument is class itself(cls).

    - Two classmethods : Declare classmethod fromDictionary using with decorator@, first argument is class itself(cls).

3. Create object

4. Call class.classmethod

 

POINT : It does not create instance. When call classmethods, class itself be called as an first argument. It creates User initiator, asign to classmethod.

 

1.
class User:

2.
    def __init__(self, email, password):
        self.email=email
        self.password=password
        
    @classmethod #
    def fromTuple(cls, tup): 
        return cls(tup[0], tup[1])
    
    @classmethod
    def fromDictionary(cls, dic):
        return cls(dic['email'], dic['password'])

3.
user=User('google@google.com','1234')
print(user.email, user.password)

4.
user=User.fromTuple(('google@google.com','1234'))
print(user.email, user.password)

 

• staticmethod

- Steps

1. Define class

2. Define two static methods

    - Define toCamelcase methods as static using decorator @staticmethod

    - Define toSnakecase methods as static using decorator @staticmethod

3. Call class.staticmethod

 

POINT : It does not create instance. There is no argument in the staticmethod.

1.
class StringUtils: 

2.
    @staticmethod
    def toCamelcase(text):
        words=iter(text.split("_"))
        return next(words)+"".join(i.title() for i in words)
    
    @staticmethod
    def toSnakecase(text):
        letters=["_"+i.lower() if i.isupper() else i for i in text]
        return "".join(letters).lstrip("_")

3.
print(StringUtils.toCamelcase('last_modified_date'))
print(StringUtils.toSnakecase('last_modified_date'))