Master Python’s @property: Turn Methods into Read‑Only Attributes

In Python, @property is a decorator used to turn a method into a read‑only attribute.

1. Purpose

Using @property creates a read‑only attribute, preventing direct modification of the underlying value while allowing attribute‑style access.

2. Usage Scenarios

2.1 Access a method like an attribute

class DataSet(object):
    @property
    def method_with_property(self):
        # contains @property
        return 15

    def method_without_property(self):
        # no @property
        return 15

l = DataSet()
print(l.method_with_property)      # called without ()
print(l.method_without_property()) # must be called with ()

Both calls output 15. Calling a @property -decorated method with parentheses raises TypeError: 'int' object is not callable because the method is now an attribute, not a callable function.

2.2 Prevent attribute modification

Python does not have true private attributes, so @property can hide internal names and expose read‑only properties.

class DataSet(object):
    def __init__(self):
        self._images = 1
        self._labels = 2

    @property
    def images(self):
        # read‑only property
        return self._images

    @property
    def labels(self):
        return self._labels

l = DataSet()
print(l.images)  # accessed as attribute, cannot be modified directly

Attempting to call the property with parentheses or trying to assign to it will result in errors, reinforcing encapsulation.