Question

If the items on the following list appeared in a problem domain description, which would be potential classes? \(\begin{array}{lll}\text { Animal } & \text { Medication } & \text { Nurse } \\\ \text { Inoculate } & \text { Operate } & \text { Advertise } \\ \text { Doctor } & \text { Invoice } & \text { Measure } \\ \text { Patient } & \text { Client } & \text { Customer }\end{array}\)

Short answer

Answer: The potential classes in the problem domain description are Animal, Medication, Nurse, Doctor, Invoice, Patient, Client, and Customer.

Step-by-step solution

Identify nouns and what they represent

Review the list and analyze each item, determine if it's a noun representing an object or concept and has attributes and behaviors: - Animal: Noun - Object - Medication: Noun - Object - Nurse: Noun - Object - Inoculate: Verb - Action/Behavior - Operate: Verb - Action/Behavior - Advertise: Verb - Action/Behavior - Doctor: Noun - Object - Invoice: Noun - Object - Measure: Verb - Action/Behavior - Patient: Noun - Object - Client: Noun - Object - Customer: Noun - Object

Select potential classes

Choose nouns that represent objects or concepts with attributes and behaviors. These are potential classes in the problem domain: - Animal - Medication - Nurse - Doctor - Invoice - Patient - Client - Customer Potential classes in the problem domain description are: Animal, Medication, Nurse, Doctor, Invoice, Patient, Client, and Customer.

Key concepts

Classes and Objects

In the world of Object-Oriented Programming (OOP), classes and objects are fundamental concepts that help us model our program after real-world entities.

A class is a blueprint for creating objects (a particular data structure), providing initial values for state (that is, for member variables or attributes), and implementations of behavior (that is, for member functions or methods). The potential classes identified, such as Animal or Doctor, would have various attributes and behaviors unique to what they represent in the real word. For example, an Animal class may have attributes like species and age, and behaviors like eat and sleep.

An object is an individual instance of a class. If you think of a class as the mold, an object would be one specific item produced from that mold. It's important to note that while classes define the type of information and actions that objects can have, each object actually contains its own unique set of values.

Let's improve our approach by focusing on the attributes and behaviors that various objects could realistically have in our program, ensuring we design our classes to fully encapsulate what an object is and can do.

Problem Domain Analysis

The process of Problem Domain Analysis involves examining the real-world context where a software solution will be applied. It's akin to a craftsman understanding the material they will work with before shaping it.

When analyzing the problem domain, we first identify the significant entities that are part of the problem space—the things that need to be represented in the program. By discerning these entities, such as the Animal, Medication, or Patient from our list, we can define what classes we might need to represent them.

As part of problem domain analysis, it's crucial not to jump to conclusions quickly but to take adequate time to understand the context and relationships. This might mean deciding whether an item like 'Invoice' is truly its own entity requiring a detailed representation, or if it can be a simple attribute of another class. We may also improve this process by talking with domain experts or users to ensure our understanding matches the real-world application.

Attribute and Behavior Identification

Once classes have been conceptualized during the problem domain analysis, the next step is to flesh them out through Attribute and Behavior Identification. This involves pinpointing what pieces of data a class should hold, and what actions it should be able to perform.

Attributes are data points that describe the state of an object. For instance, a Nurse might have attributes like 'name', 'employeeID', and 'qualification'. We aim to choose attributes that are integral to the identity of the object and necessary for the interactions it will have within the program.

On the other hand, behaviors are like actions or functions that an object can perform. These could be methods within a class that do something with or to the object's attributes. For example, a Customer might have a behavior like 'makePurchase()' or 'registerComplaint()'.

To enhance our solution, we ensure we clearly define each class's attributes and behaviors, representative of their real-world counterparts. This can involve creating detailed UML diagrams or simply listing out attributes and behaviors in a structured format to ensure no critical aspect of the real-world entity is overlooked in our representation.