Python self是什麼

類變量和實例變量

• 類變量可以被所有的實例使用

• 所有實例得到的類變量相同

• 實例變量屬於實例

Class SomeClass:

    variable_1 = “ This is a class variable”

    variable_2 = 100    #this is also a class variable.

 

    def __init__(self, param1, param2):

        self.instance_var1 = param1

        #instance_var1 is a instance variable

         self.instance_var2 = param2   

        #instance_var2 is a instance variable

類變量

>>> obj1 = SomeClass("some thing", 18)

#creating instance of SomeClass named obj1

>>> obj2 = SomeClass(28, 6)

#creating a instance of SomeClass named obj2

 

>>> obj1.variable_1

'a class variable'

 

>>> obj2.variable_1

'a class variable'

實例變量

>>> obj1.instance_var1

'some thing'

>>> obj2.instance_var1

28

類函數和實例函數

實例函數

class SomeClass:    

    def create_arr(self): # An instance method

        self.arr = []

    

    def insert_to_arr(self, value):  #An instance method

        self.arr.append(value)

 

>>> obj3 = SomeClass()

>>> obj3.create_arr()

>>> obj3.insert_to_arr(5)

>>> obj3.arr

[5]

類函數

class SomeClass:

    def create_arr(self): # An instance method

        self.arr = []

    

    def insert_to_arr(self, value):  #An instance method

        self.arr.append(value)

        

    @classmethod

    def class_method(cls):

        print("the class method was called")

不用實例化，直接用類名調用類函數

SomeClass.class_method()

self

class SomeClass:

    def __init__(self):

        self.arr = []

        #All SomeClass objects will have an array arr by default

    

    def insert_to_arr(self, value):

        self.arr.append(value)

 

obj1 = SomeClass()

obj2 = SomeClass()

obj1.insert_to_arr(6)

Python將上面obj1調用轉爲如下

SomeClass.inseart_to_arr(obj1, 6)

 

參考資料：

https://medium.com/quick-code/understanding-self-in-python-a3704319e5f0