python creates a class using the metaclass type
- 2021-12-11 08:32:52
- OfStack
Foreword:
Usually we create classes using
class
Class name, but have your friends ever wondered who created the class?
python
It is often said that everything is an object, and an object is created by a class. That class itself can also be regarded as an object, and a class can be made of a metaclass
type
Create
1. type dynamically creates classes
1.1 Syntax Format
type(Class name, tuple of parent class name (can be empty), dictionary containing attributes (name and value))
1.2 Case 1: Creating a Class Using type
Person = type("Person", (), {})
p = Person()
print(type(p))
print(Person.__name__)
Results:
<class '__main__.Person'>
Person
Note: Person in type ("Person", (), {}) can be written as any other string, but when you print the name of the class, it will become that you write other strings
Person = type("Per", (), {})
p = Person()
print(Person.__name__)
Results:
Per
Therefore, in order to make the program code more friendly, 1 general variable names and set class names remain the same 1
1.3 Case 2: Creating a Class with Attributes (Methods) Using type
def show(self):
print(" Show yourself ")
Person = type("Person", (), {"age": 18, "name": "jkc", "show": show})
p = Person()
print(p.age)
print(p.name)
p.show()
Results:
18
jkc
Show yourself
We dynamically created a parent class for
Object
The attributes are
age
,
name
The method is
show
Class of
1.4 Case 3: Using type to dynamically create a class that inherits the specified class
class Animal:
def __init__(self, color="blue"):
self.color = color
def eat(self):
print(" Eat ")
Dog = type("Dog", (Animal, ), {})
dog = Dog()
dog.eat()
print(dog.color)
Results:
Eat
blue
We dynamically created an inheritance
Animal
Class
Dog
Class, you can use the
Animal
All methods and properties of the class