How to decorate a class in Python?

It uses additional Python statements to modify the old object and return the same reference.

For example, consider the following class, which has two methods: __init__ and display. The __init__ method initializes the name variable when displaying the output name:

class Student:
def __init__(self, name):
self.name = name
def display(self):
print('Name:', self.name)

To decorate this class in Python, we can add new methods to the class or modify existing methods, or both.

Also, there are two ways to do this in Python, either using a function decorator or a class decorator.

Let’s look at the examples one by one.

Decorating a class using a function decorator

To use a function decorator to decorate a class, accept the class as a parameter, modify its code and return the class at the end.

def mydecorator(student):
#define a new display method
def newdisplay(self):
print('Name: ', self.name)
print('Subject: Programming')
#replace the display with newdisplay
student.display = newdisplay

#return the modified student
return student
@mydecorator
class Student:
def __init__(self, name):
self.name = name
def display(self):
print('Name:', self.name)
obj = Student('Pencil Programmer')
obj.display()
'''
Name: Pencil Programmer
Subject: Programming
'''

If the display method does not exist in the class, newdisplay will be added to the class as a display method.

• Since the reference to the class is available in the decorator function, in addition to modifying the existing methods, we can also add new properties and methods to the class
  

Decorating a class using a class decorator

To decorate a class using a class decorator, accept a reference to the class as a parameter (in the decorator's __init__ method), in __call__ Modify its code in the method, and finally return an instance of the modified class.

class Mydecorator:
#accept the class as argument
def __init__(self, student):
self.student = student

#accept the class's __init__ method arguments
def __call__(self, name):
#define a new display method
def newdisplay(self):
print('Name: ', self.name)
print('Subject: Python')

#replace display with newdisplay
self.student.display = newdisplay

#return the instance of the class
obj = self.student(name)
return obj
@Mydecorator
class Student:
def __init__(self, name):
self.name = name

def display(self):
print('Name: ', self.name)
obj = Student('Pencil Programmer')
obj.display()
'''
Name: Pencil Programmer
Subject: Python
'''

The only difference here is that we return an object reference instead of a class reference.

Original text:​​https://www.php.cn/link/137ffea9336f8b47a66439fc34e981ee​​

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