Python vars() Function
Python3 Built-in Functionsvars()is a built-in function in Python for returning an object's__dict__attributes.
vars()Returns a dictionary containing all writable attributes of the object. For objects lacking__dict__a __dict__, a TypeError exception is raised.
Word Definitions： vars 是 variables（变量）的缩写。
Basic Syntax and Parameters
Syntax Format
vars(object)
Parameter Description
- Parameter object：
- Type: Any object
- Description: The object whose attributes are to be obtained.
Function Description
- Return Value: returns the object's
__dict____dict__ dictionary. - Note: when called without arguments, it is equivalent to locals()
locals()。
Examples
Example 1: Viewing Object Attributes
Example
class Person:
def __init__(self, name, age):
self.name = name
self.age = age
p = Person("Tom", 20)
# View the object's __dict__
print(vars(p))
# Output: {'name': 'Tom', 'age': 20}
# Access the dictionary
print(vars(p)["name"]) # Output: Tom
def __init__(self, name, age):
self.name = name
self.age = age
p = Person("Tom", 20)
# View the object's __dict__
print(vars(p))
# Output: {'name': 'Tom', 'age': 20}
# Access the dictionary
print(vars(p)["name"]) # Output: Tom
Expected Output:
{'name': 'Tom', 'age': 20}
Tom
Code Analysis:
- vars() returns a dictionary of the object's instance attributes.
- Attributes can be accessed directly through the dictionary.
Example 2: Module and Class __dict__
Example
# The module's __dict__
import os
print(len(vars(os))) # Output: the number of attributes of the os module
# The class's __dict__ (excluding instance attributes)
class MyClass:
class_attr = 100
def __init__(self):
self.instance_attr = 200
print(vars(MyClass))
# Output: {'__module__': '__main__', 'class_attr': 100, '__init__': ...}
import os
print(len(vars(os))) # Output: the number of attributes of the os module
# The class's __dict__ (excluding instance attributes)
class MyClass:
class_attr = 100
def __init__(self):
self.instance_attr = 200
print(vars(MyClass))
# Output: {'__module__': '__main__', 'class_attr': 100, '__init__': ...}
Output:
vars() is very helpful for understanding object structure.
vars()It is often used for debugging and dynamic attribute access.
Other Extensions