Manage and Use Instance Properties

Q

How to manage and use instance properties?

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A

Instance properties, also called instance attributes, are name value pairs associated with class instance object, and not shared with other instances created from this class.

You can manage and use instance properties in various places:

1. In the class "__init__()" method statement block - You can add new instance property and assign its initial value in the class "__init__()" method statement block. In this case, you need to use the instance name and the property name in the dot (.) expression format to identify the property: instance_name.property_name. For example:

>>> class user():
...     nextID = 1
...     def __init__(self,name="Joe",age=25):
...         self.id = user.nextID
...         self.name = name
...         self.age = age
...         ...

In the above example, "self.id", "self.name" and "self.age" represents 3 instance properties.

3. In any Python code after the instance is created - You can add new instance property, assign its initial value, access its value and change its value in any Python code after the instance is created. In this case, you need to use the instance name and the property name in the dot (.) expression format to identify the property: instance_name.property_name. For example:

>>> class user():
...     ...
...
>>> x = user()
>>> x.name
'Joe'
>>> x.remark = "Smart guy!"
>>> x.remark
'Smart guy!'

 

Defining and Using Class for New Data Types

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2017-09-12, 117👍, 0💬