Python setattr() Function

In Python, the setattr() function is used to dynamically set an object's attribute value.

Function Syntax

setattr(object, name, value)

Parameters:

• object: The object whose attribute is to be set.
• name: The name of the attribute.
• value: The value to set for the attribute.

If the object already has an attribute with the same name, its value will be overwritten.

Examples of the setattr() Function

Basic usage:

class Person:
    pass

p = Person()
setattr(p, 'age', 30)
print(p.age)   # 30

Commonly used for dynamically setting attributes:

class Config:
    pass

cfg = Config()

attributes = {
    'host': 'localhost',
    'port': 8080,
    'timeout': 30
}

for key, value in attributes.items():
    setattr(cfg, key, value)

print(cfg.host)     # localhost
print(cfg.port)     # 8080
print(cfg.timeout)  # 30

Dynamically creating a class and setting attributes:

def create_dynamic_class(class_name, **kwargs):

    DynamicClass = type(class_name, (), {})

    instance = DynamicClass()

    for key, value in kwargs.items():
        setattr(instance, key, value)
    
    return instance

cfg = create_dynamic_class(
    'Config',
    host='localhost',
    port='8080',
    timeout=30
)

print(type(cfg))  # <class '__main__.Config'>
print(cfg.host)   # localhost
print(cfg.port)   # 8080
print(cfg.timeout) # 30