@property
- Python course
- Intermediate
- Lesson 19/116
- 5 min
Learn to define properties with @property.
The @property decorator
The @property decorator turns a method into something readable like an attribute. You access it without parentheses; this gives the outside a clean encapsulated look.
Example: class Account:\n @property\n def balance(self):\n return self._balance. Writing a.balance calls the method; not a.balance(). This makes it easy to update the inner logic later without changing how outside code accesses it; you can add computation, for instance.
Access without parentheses
A method marked with @property is called without parentheses. Writing a.balance is enough; a.balance() raises an error. This hides the difference between an attribute and a computed value from the outside.
So today it returns self._balance; tomorrow it can do a computation, while outside code stays unchanged. This is the core of encapsulation: stable outer interface, flexible inner data. Example: return self._balance * self._rate.
Practice Add @property to Account
Define the Account class. Add def __init__(self, balance): with self._balance = balance in the body. Above add the @property decorator and a method def balance(self):; in its body write return self._balance. Then create an instance with a = Account(100) and call print(a.balance).
Starter code
# Add a property to the Account classSample solution
# Define the Account class with @property
class Account:
def __init__(self, balance):
self._balance = balance
@property
def balance(self):
return self._balance
a = Account(100)
print(a.balance)Expected output
100
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 Complete the @property line
____
def balance(self):
return self._balance @property
def balance(self):
return self._balanceExplanation: The @property decorator turns the method into a readable attribute.
2 What does @property do?
- It deletes an attribute
- It creates a class variable
- It makes a method read like an attribute Correct answer
- It makes a method static
Explanation: @property makes a method read like an attribute; no parentheses needed.
3 Match the @property concepts
| Term | Meaning |
|---|---|
@property |
Getter decorator |
a.balance |
Parenthesis-free access |
self._balance |
Inner data |