A brief introduction to the property function in Python

This article brings you a brief introduction to the property function in Python. It has certain reference value. Friends in need can refer to it. I hope it will be helpful to you.

Using the Property function in Python, you can call functions in a class as attributes.

Case

__metaclass__=type
class Rectangle:
    def __init__(self):
        self.width=0
        self.height=0
    def setSize(self,size):
        self.width,self.height=size
    def getSize(self):
        return self.height,self.width
    size=property(getSize,setSize)
r=Rectangle()
r.width=10
r.height=5
ret=r.size
print(ret)
r.size=100,50
rets=r.width
print(rets)

Output result:

(5, 10)
100

Property function An attribute size is created, and the accessor function is used as a parameter (value is obtained first, then assigned). Although they look like properties, the properties of size still depend on the calculations of getSize and setSize.

In fact, Property is not a real function but a class with a lot of special methods, and it is these methods that can complete all the work. Involved methods:

#The above three methods define the rules of descriptors. The object that implements any one of these methods is called a descriptor. What's special about descriptors is how they are accessed. For example, when a program reads a property, if the property is bound to an object that implements the __get__ method, the __get__ method will be called instead of simply returning the object. This is the property mechanism of the object, also called the binding method.

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