


How to use the getattr() function in Python to obtain the attribute value of an object
Aug 22, 2023 pm 03:00 PMHow 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 function getattr()
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 the getattr()
function in detail and provide actual code examples for better understanding.
getattr()
The syntax of the function is as follows:
getattr(object, name[, default])
Among them, object
is the object to obtain the attribute value, name
is the name of the attribute. The optional default
parameter indicates the default value returned when the attribute does not exist. The default is None
.
Then let’s look at a few examples to demonstrate the usage of the getattr()
function. First, we define a simple class Person
:
class Person: def __init__(self, name, age): self.name = name self.age = age
Next, we instantiate a Person
object and define name## for it #And
ageTwo attributes:
person = Person("Alice", 25)Now, we can use the
getattr() function to get the attribute value of the object. For example, we can get the
name attribute value of the
person object:
name = getattr(person, "name") print(name) # 輸出:AliceSimilarly, we can also get the
of the person
object ageAttribute value:
age = getattr(person, "age") print(age) # 輸出:25We can also use the
getattr() function to get attributes that do not exist in the object. By default, the
getattr() function returns
None. For example, we try to get the
gender attribute of the
person object:
gender = getattr(person, "gender") print(gender) # 輸出:NoneIf we want to customize the default value when the attribute does not exist, we can use
getattr ()The third parameter of the function
default. For example, we define a
gender attribute with a default value of
"Unknown", and then try to get its value:
gender = getattr(person, "gender", "Unknown") print(gender) # 輸出:UnknownIn 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 function
get_age() to obtain the
age attribute value of the
person object:
def get_age(obj): return obj.age age = getattr(person, get_age) print(age) # 輸出:25It 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 the
getattr() 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 the
getattr() function.
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