Property decorator usage in Python - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of the @property decorator in Python?

The @property decorator allows you to define a method that can be accessed like an attribute. It helps to control access to instance variables while keeping the syntax simple and clean.

intermediate

How do you define a setter method for a property in Python?

You define a setter method by using the @property_name.setter decorator above a method with the same name as the property. This method allows you to set the value while controlling or validating it.

beginner

What happens if you try to set a value to a property without defining a setter?

If no setter is defined, trying to assign a value to the property will raise an AttributeError. This protects the property from being changed directly.

beginner

Explain the difference between a regular method and a property method in Python.

A regular method requires parentheses to be called (e.g., obj.method()), while a property method can be accessed like an attribute without parentheses (e.g., obj.property). Properties provide a way to use methods as if they were attributes.

beginner

Show a simple example of a class with a property and a setter using the <code>@property</code> decorator.

Example:<br><pre>class Person:
    def __init__(self, name):
        self._name = name

    @property
    def name(self):
        return self._name

    @name.setter
    def name(self, value):
        if not value:
            raise ValueError('Name cannot be empty')
        self._name = value

p = Person('Alice')
print(p.name)  # Outputs: Alice
p.name = 'Bob'  # Sets new name
</pre>

What does the @property decorator do in Python?

A Turns a method into a read-only attribute

B Defines a class method

C Creates a static method

D Deletes an attribute

The @property decorator makes a method behave like a read-only attribute.

How do you define a setter for a property named age?

A Using <code>@age.set</code>

B Using <code>@property.setter</code>

C Using <code>@set_age</code>

D Using <code>@age.setter</code> above the setter method

The setter for a property age is defined with @age.setter.

What error occurs if you try to set a property without a setter?

A NameError

B AttributeError

C ValueError

D TypeError

Trying to set a property without a setter raises an AttributeError.

Which of these is a benefit of using properties?

A Control access to attributes with simple syntax

B Make methods run faster

C Allow multiple inheritance

D Automatically document code

Properties let you control attribute access while keeping syntax clean.

How do you access a property method in Python?

A Using square brackets

B With parentheses like a normal method

C Like an attribute, without parentheses

D Using the <code>get()</code> function

Property methods are accessed like attributes, without parentheses.

Explain how the @property decorator works and why it is useful.

Think about how you can hide internal details but still let users get or set values easily.

Describe how to create a property with both getter and setter methods in a Python class.

Remember the setter decorator uses the property name.