Question

What is an accessor? What is a mutator?

Short answer

An accessor, or getter method, is a function in a class or object that retrieves the value of a private attribute without directly accessing it. It helps maintain data integrity and security by promoting encapsulation and data hiding in object-oriented programming. A mutator, or setter method, is a function in a class or object that modifies the value of a private attribute by validating its input data to maintain data integrity and security. Both accessors and mutators prevent unauthorized access to an object's data. Examples of an accessor and mutator can be seen in Python's `get_name()` and `set_name()` methods in the Student class, where the private attribute `__name` is retrieved or modified without direct access.

Step-by-step solution

Definition of an Accessor

An accessor, also known as a "getter" method, is a function or method in a class or an object that allows you to retrieve the value of a private or protected attribute without directly accessing it. Accessors help to maintain the integrity and security of an object's data by preventing unauthorized access. It promotes the principle of encapsulation and data hiding in object-oriented programming.

Example of an Accessor

An example of an accessor might be the following code in Python: ```python class Student: def __init__(self, name): self.__name = name def get_name(self): return self.__name ``` In this example, the `get_name()` method is an accessor. It returns the value of the private attribute `__name` without directly accessing it.

Definition of a Mutator

A mutator, also known as a "setter" method, is a function or method in a class or an object that allows you to modify (set or update) the value of a private or protected attribute. Like accessors, mutators also help to maintain the integrity and security of an object's data by preventing unauthorized access and allowing validation of the input data.

Example of a Mutator

An example of a mutator might be the following code in Python: ```python class Student: def __init__(self, name): self.__name = name def set_name(self, new_name): if isinstance(new_name, str) and len(new_name) > 0: self.__name = new_name else: raise ValueError("Invalid name.") ``` In this example, the `set_name()` method is a mutator. It sets the value of the private attribute `__name` by taking a new value (`new_name`) as an input, validating the input, and then updating `__name` accordingly.