Meta-class correlation (Type & metaclass)

"""
Metaclass Effect:

1) Creation of interception classes

2) Modify the class

3) return the modified class

"""

"""
Why use the Metaclass class instead of the function?

Since __metaclass__ can accept any callable object, why use a class, because it is obviously more complex to use the class? There are several reasons for this:

1) intentions will be clearer. When you read Upperattrmetaclass (type), you know what's going to happen next.

2) You can use OOP programming. A meta-class can inherit from a meta-class, overwriting the method of the parent class. A meta class can even use a meta class.

3) You can organize the code better. When you use the meta-class, it's certainly not a simple scenario like the one I've mentioned above, and it's usually about more complex issues. It can be helpful to which comes multiple methods into a class and make the code easier to read.

4) You can use special methods such as __new__, __init__ and __call__. They can help you with different tasks. Even if you can usually dispose of everything in __new__, some people still feel more comfortable with __init__.

5) Wow, the name of this thing is metaclass, certainly non-angel, I have to be careful!

Why should we use meta-classes?

Now back to our big theme, why are you going to use such an error-prone and obscure feature? Well, generally speaking, you don't use it at all:

"Meta-class is the magic of depth, 99% of users should not worry about it at all." If you want to figure out whether you need to use a meta-class, then you don't need it. Those who actually use the meta-class know very well what they need to do and do not need to explain why they use the meta-class at all. "The leader of the--python world Tim Peters
"""

"""
Knowledge Points:
objects are class-created. When you create an object, the __init__ method inside the class executes automatically. The object () executes the __call__ method of the class.
Class is a type created. When you create a class, the __init__ method of type is automatically executed. Class () Executes the __call__ method that executes the type. After the __call__ method is executed, the call method calls not only the __new__ method of the class, but also the __init__ method of the class.

#No. 0 Step: Execute the __init__ method of type "class is an object of type"classFoo:def __init__(self):Passdef __call__(Self, *args, * *Kwargs):Pass#1th Step: Execute the __call__ method of type#1.1 calls the __new__ method of the Foo class (the object of type), which is used to create the object. #1.2 calls the __init__ method of the Foo class (the object of type), which is used to initialize the object. obj =Foo ()#2nd step: Execute foo def __call__ methodObj ()

"""

Meta-class correlation (Type & metaclass)