How to use the setattr() function in Python to set the attribute value of an object

How to use the setattr() function in Python to set the attribute value of an object

In Python, we can use the setattr() function to dynamically set the attribute value of an object. The setattr() function is a built-in function that accepts three parameters: object, attribute name and attribute value. By calling this function, we can dynamically set the object's property value at runtime without knowing the name of the property in advance.

Let’s look at an example below to demonstrate how to use the setattr() function to set the attribute value of an object:

class Person:
    pass

p = Person()

setattr(p, 'name', 'John')
setattr(p, 'age', 25)

print(p.name)  # 输出：John
print(p.age)  # 输出：25

In the above code, we first define a Person class and create a An object named p. Then, we use the setattr() function to set the values ​​of the name and age attributes for the p object respectively. Finally, we print out the values ​​of the name and age attributes of the p object.

As you can see, through the setattr() function we can dynamically set the attribute values ​​of the object at runtime. This is very useful in certain situations, such as when we obtain the attribute name and corresponding value from some external source, we can directly use the setattr() function to set the attribute value of the object without explicitly defining the attribute. .

Next, let’s look at a slightly more complex example that demonstrates how to use a loop and a dict object to set the value of multiple properties at once:

class Person:
    pass

p = Person()

attributes = {
    'name': 'John',
    'age': 25,
    'city': 'New York'
}

for attr, value in attributes.items():
    setattr(p, attr, value)

print(p.name)  # 输出：John
print(p.age)  # 输出：25
print(p.city)  # 输出：New York

In the above code, we first A Person class is defined and an object named p is created. Then, we define a dictionary object attributes that contains multiple attributes and corresponding values. Next, we use a loop to iterate through each attribute and value in the dictionary and set it to the attribute value of the p object using the setattr() function. Finally, we print out all attribute values ​​of the p object.

As you can see, by using loops and dict objects, we can set the values ​​of multiple attributes at once, further simplifying the code.

To summarize, the setattr() function in Python can easily set the attribute values ​​of an object dynamically at runtime. Whether setting the value of a single property or setting the value of multiple properties at once, by using the setattr() function, we can operate the properties of the object more flexibly. I hope this article can help you understand and use the setattr() function.

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