#Python's member visibility
You can access object members through object.member:
# Define class
class Cat:
"""
Cat class
"""
def __init__(self, name: str):
"""
Constructor
Args:
name (str): Name
"""
self.name = name # Create name attribute
# Create a group of cats
cat1 = Cat("Tom")
cat2 = Cat("Happy")
cat3 = Cat("San San")
# Access name attribute
print(cat1.name)
print(cat2.name)
print(cat3.name)
# Modify name attribute
cat1.name = 'Schrödinger'
print(cat1.name)
#Private Members
Private variables can only be accessed by the object that owns them, i.e., they can only be read or modified through the object's own methods. Recall the naming conventions:
- Private variables use two leading underscores, e.g.,
__age_of_yukari
Methods can also be made private using this naming style.
For example, to make the cat's name a private attribute, provide a name method to read it and a set_name method to modify it, and forbid naming the cat "Schrödinger":
# Define class
class Cat:
"""
Cat class
"""
def __init__(self, name: str):
"""
Constructor
Args:
name (str): Name
"""
self.__name = name # Create private __name attribute
def name(self) -> str:
"""
name method to get the cat's name
Returns:
str: The cat's name
"""
return self.__name
def set_name(self, name: str) -> bool:
"""
set_name method to set the cat's name
Args:
name (str): Name to set
Returns:
bool: Whether setting the name was successful
"""
if name == "Schrödinger":
return False
self.__name = name
return True
# Create object
cat = Cat("Garfield")
print(cat.name())
# Try to access __name directly
try:
print('Directly reading __name succeeded:', cat.__name)
except Exception as e:
print('Directly reading __name failed')
# Try setting name to Schrödinger
cat.set_name("Schrödinger")
print(cat.name())
This shows how to control member visibility in Python classes using private attributes and methods.