SOLID Principles in Laravel: A Cyberpunk AI Guide, Part 3

Part 3: The Liskov Substitution Principle

The Liskov substition principle (LSP) states that ‘functions that use pointers or references to base classes must be able to use objects of derived classes without knowing it”, or in other words, “subtypes must be substitutable for their base types”, or in even more words “objects of a superclass should be replaceable with objects of a subclass and still maintain correctness”.

Our cyberpunk world is a world where AI systems are heavily integrated into society. There are various types of AI systems, including ones that can perform tasks in hazardous environments and ones that can provide medical assistance to humans.

Now, let’s say that there is a base class called “AI system” that defines the basic behavior and capabilities of all AI systems. There are also derived classes called “Hazardous Environment AI” and “Medical AI” that represent AI systems that are specialized for those specific purposes.

According to the LSP, it should be possible to use an instance of the derived class anywhere that an instance of the base class is expected, without causing any issues or breaking any functionality. In other words, the derived class should be a “substitute” for the base class.

This means that if a program is written to work with any type of AI system, it should be able to use a Hazardous Environment AI or a Medical AI just as easily as it could use a general-purpose AI system. It should not have to worry about whether the AI system is specialized or not, as long as it meets the basic requirements defined by the base class.

The interfaces and classes:

<?php

// This is the interface that defines the basic behavior and capabilities of all AI systems
interface AISystem
{
    // Some basic methods that all AI systems should have
    public function receiveInput($input);
    public function processInput();
    public function generateOutput();
}

// This is the interface that defines additional methods for AI systems that work in hazardous environments
interface HazardousEnvironmentAI
{
    public function activateProtectiveShields();
    public function detectHazards();
}

// This is the interface that defines additional methods for AI systems that provide medical assistance
interface MedicalAI
{
    public function diagnosePatient();
    public function prescribeTreatment();
}

// This is a class that represents an AI system specialized for hazardous environments
class HazardousEnvironmentAI implements AISystem, HazardousEnvironmentAI
{
    // Implementations of the basic methods defined in the AISystem interface
    public function receiveInput($input) {}
    public function processInput() {}
    public function generateOutput() {}

    // Implementations of the methods defined in the HazardousEnvironmentAI interface
    public function activateProtectiveShields() {}
    public function detectHazards() {}
}

// This is a class that represents an AI system specialized for medical assistance
class MedicalAI implements AISystem, MedicalAI
{
    // Implementations of the basic methods defined in the AISystem interface
    public function receiveInput($input) {}
    public function processInput() {}
    public function generateOutput() {}

    // Implementations of the methods defined in the MedicalAI interface
    public function diagnosePatient() {}
    public function prescribeTreatment() {}
}

For a controller example, we could do something like:

<?php

namespace App\Http\Controllers;

use App\AI\MedicalAI;
use Illuminate\Http\Request;

class MedicalAIController extends Controller
{
    public function performTask(Request $request, MedicalAI $ai)
    {
        $ai->receiveInput($request->input('task_instructions'));
        $ai->processInput();
        $output = $ai->generateOutput();

        // The function can then use the output to accomplish the desired task
        // (the specifics of this will depend on the task being performed)

        return response()->json([
            'success' => true
        ]);
    }
}

And the route:

Route::post('/ai/perform-task', [MedicalAIController::class, 'performTask']);