How to use the getattr() function in Python to obtain the attribute value of an object-Python Tutorial-php.cn

How to use the getattr() function in Python to obtain the attribute value of an object

In Python programming, we often encounter situations where we need to obtain the attribute value of an object. Python provides a built-in functiongetattr()to help us achieve this goal.getattr()The function allows us to get the attribute value of the object by passing the object and attribute name as parameters. This article will introduce the usage of thegetattr()function in detail and provide actual code examples for better understanding.

getattr()The syntax of the function is as follows:

getattr(object, name[, default])

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Among them,objectis the object to obtain the attribute value,nameis the name of the attribute. The optionaldefaultparameter indicates the default value returned when the attribute does not exist. The default isNone.

Then let’s look at a few examples to demonstrate the usage of thegetattr()function. First, we define a simple classPerson:

class Person: def __init__(self, name, age): self.name = name self.age = age

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Next, we instantiate aPersonobject and definename## for it #AndageTwo attributes:

person = Person("Alice", 25)

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Now, we can use the

getattr()function to get the attribute value of the object. For example, we can get thenameattribute value of thepersonobject:

name = getattr(person, "name") print(name) # 输出：Alice

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Similarly, we can also get the

of thepersonobject ageAttribute value:

age = getattr(person, "age") print(age) # 输出：25

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We can also use the

getattr()function to get attributes that do not exist in the object. By default, thegetattr()function returnsNone. For example, we try to get thegenderattribute of thepersonobject:

gender = getattr(person, "gender") print(gender) # 输出：None

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If we want to customize the default value when the attribute does not exist, we can use

getattr ()The third parameter of the functiondefault. For example, we define agenderattribute with a default value of"Unknown", and then try to get its value:

gender = getattr(person, "gender", "Unknown") print(gender) # 输出：Unknown

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In addition to getting it through the attribute name string In addition to the attribute value of the object, the

getattr()function can also accept a callable object as the attribute name. This callable object will find the attribute name in the object. For example, we define a functionget_age()to obtain theageattribute value of thepersonobject:

def get_age(obj): return obj.age age = getattr(person, get_age) print(age) # 输出：25

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It should be noted that when When using a callable object as a property name, the callable object still needs to return the correct property value.

To sum up, the

getattr()function is a very useful function, which can help us get the attribute value of an object in programming. We can use thegetattr()function by passing the object and property name, and can also set default values and use callable objects as property names. I hope the sample code in this article can help you better understand the usage of thegetattr()function.

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