Python property() Built in Function

The property() function is used to create and return a property object that has a getter, a setter, and a deleter method. The syntax of this function is:

property(fget=None, fset=None, fdel=None, doc=None)

The fget parameter is optional and specifies a function to get the value of the attribute. The fset parameter is optional and specifies a function to set the value of the attribute. The fdel parameter is optional and specifies a function to delete the attribute. The doc parameter is optional and specifies a string that serves as the documentation for the attribute.

The property() function can be used as a decorator or as a normal function. Here are some examples of using the property() function in Python:

To create a read-only property using @property decorator:

class Person:
    def __init__(self, name):
        self._name = name # private attribute

    @property
    def name(self): # getter method
        return self._name

p = Person("Alice")
print(p.name) # prints Alice
p.name = "Bob" # raises AttributeError

To create a read-write property using @property decorator and setter method:

class Person:
    def __init__(self, name):
        self._name = name # private attribute

    @property
    def name(self): # getter method
        return self._name

    @name.setter
    def name(self, value): # setter method
        if not isinstance(value, str):
            raise TypeError("Name must be a string")
        self._name = value

p = Person("Alice")
print(p.name) # prints Alice
p.name = "Bob" # sets name to Bob
print(p.name) # prints Bob
p.name = 42 # raises TypeError

To create a property using property() function as a normal function:

class Person:
    def __init__(self, name):
        self._name = name # private attribute

    def get_name(self): # getter method
        return self._name

    def set_name(self, value): # setter method
        if not isinstance(value, str):
            raise TypeError("Name must be a string")
        self._name = value

    def del_name(self): # deleter method
        del self._name

    name = property(get_name, set_name, del_name) # creates property object

p = Person("Alice")
print(p.name) # prints Alice
p.name = "Bob" # sets name to Bob
print(p.name) # prints Bob
del p.name

If you have any questions about this code, you can drop a line in comment.

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