How to use self in python

Before introducing Pyhton’s self,we should to talk about class and instance.

We kown that the most concept of object-oriendted is the class and instance.The class is an abstract template.For examplem the People is a abstract object can be represented by a People class.An instance is a concrete “object” crected from classes.Each object inherits the same method,but the respective data may be different.

You can see the Class People:
```
 class People(oject):
     pass
```
Object indicates which class the class inherits from,and the Object class is a class that all classes inherits.
Instance: How to create a People instance after define a People class.You can create by the class name + (),pass to a variable:
```
People=People()
```

Because the class is a template, we can bind the attributes into the instance when we create.Here we us the __init__() which is a built-in function in Python:

 1 |Class People(object):
 2 | Def __init__(self, name, High):
 3 |     Self.name = name
 4 |     Self.High = High

Note:

The first parameter of the __init__ () function is always self,it meams that self is the instance of created class.So we can bind the attributes with self in __init__().
If you define the __init__(), We must pass in parameters that match the __init__() function, cannot pass empty parameters when we create instance.But self does not need to be passed,the Python interpreter will passed itself.
```
  1|>>>People = People("Tom", 166)
  2|>>>People.name 
  3|"Tom"
  4|>>>People.High
  5|166
```
In this way we can package this class very well. The external only needs to call the inside variable without knowing the internal implementation details inside.(Everything is an object in Python)
To make the class more secure, we can call these private attributes and public attributes. Like This:


private attributes	“__name”
public attributes	“name”

class People(object):
    def set_High(self, High):
        self.__High = High

>>> People = People('Tom', 166)
>>> People.__name
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'People' object has no attribute '__name'

Cannot arbitrarily change internal important attributes, safe and robust.