Abstract Base Classes

Easy

Imagine you have different kinds of toys like cars, dolls, and blocks. Now, what if I told you that there’s something special about all of them that makes them toys? That special thing is what we call an “abstract base class.”

Think of it like this: An abstract base class is like a blueprint for making different kinds of toys. It tells us what all toys should have in common, like wheels for cars or arms and legs for dolls. But it doesn’t make any specific toys itself.

So, when we make a new toy, we use this blueprint to make sure it has all the important stuff. But each toy can still be unique, like having different colors or shapes.

In simple words, abstract base classes help us make sure all toys follow certain rules, even though they can still be different from each other. Just like how all cars have wheels, but they can be different colors and sizes.

Another easy example

Imagine you’re making a game with different types of animals. You want all the animals to be able to make a sound, but each animal will make a different noise.

A regular class would be like a basic animal template. It might have properties like color, size, and maybe even a general “move” function. But how the animal moves would be different for a dog (walk, run) or a bird (fly).

An abstract base class is like a special template that says all animals must have a way to make a sound, but it doesn’t say exactly how. It’s like a rule in your game that all animals need to have a “make_sound” function.

Here’s the cool part: You can’t create an animal directly from this abstract base class, because it’s missing the specific sound. It’s like a blueprint that’s not quite finished.

Instead, you create different classes for specific animals like dogs and birds. These classes inherit from the abstract base class, and they have to provide their own way of making a sound — woof for dogs and tweet for birds.

So, the abstract base class makes sure all your animals (dogs, birds, etc.) can make a sound, but it lets each kind of animal have its own unique way of doing it! This helps keep your game organized and makes it easier to add new animals later — as long as they can make a sound, of course!

Moderate

So, imagine you’re playing with building blocks. You can stack them on top of each other to make all sorts of things, like houses or towers. But what if you want to make sure that every time you build something, it has a certain feature? For example, maybe you always want your buildings to have a door.

In programming, an abstract base class is kind of like a special blueprint for building blocks. It defines the features that any class based on it must have. So if we wanted to make sure that every building we create has a door, we could create an abstract base class called “Building” that includes a “door” feature. Then, when we create new classes for specific types of buildings (like houses or towers), they would automatically include a door because they are based on the Building class.

So in short, an abstract base class is a way to define shared features and behavior for a group of related classes, so that you don’t have to repeat yourself over and over again.

Hard

Abstract Base Classes (ABCs) are a feature of object-oriented programming languages that allow you to define a common interface for derived classes. They are used to define a template for other classes, specifying a set of methods that must be created within any child classes built from the abstract class. ABCs cannot be instantiated on their own; they are meant to be subclassed.

Here are some key points about Abstract Base Classes:

1. Purpose: The primary purpose of an ABC is to define a common interface for its subclasses. This interface can include method signatures that the subclasses must implement.

2. Abstract Methods: ABCs can define abstract methods, which are methods declared in the ABC but do not contain any implementation. Subclasses of the ABC are required to provide an implementation for these methods.

3. Concrete Methods: In addition to abstract methods, ABCs can also define concrete methods, which are methods that have a default implementation. Subclasses can inherit these methods as-is or override them with their own implementation.

4. Instantiation: You cannot create an instance of an ABC directly. The purpose of an ABC is to serve as a blueprint for other classes, not to be used as a standalone object.

5. Use Cases: ABCs are useful in situations where you want to ensure that certain classes share a common set of methods or properties. This is particularly useful in designing frameworks or libraries where you want to enforce a consistent interface across different components.

6. Implementation: The implementation of ABCs can vary between programming languages. For example, in Python, you use the abc module and the @abstractmethod decorator to define abstract methods. In Java, you use the abstract keyword to define an abstract class and abstract methods.

7. Benefits: Using ABCs can lead to more robust and maintainable code. By defining a common interface, you ensure that all subclasses adhere to the same contract, making it easier to work with different implementations of the same interface.

In summary, Abstract Base Classes are a powerful tool in object-oriented programming that allow you to define a common interface for a group of related classes, ensuring that they all implement certain methods and adhere to a specific contract.

A few books on deep learning that I am reading:

Book 1

Book 2

Book 3