Prompt Engineering Tips with GitHub Copilot

GitHub Copilot, powered by OpenAI, is changing the game in software development. It's not just a tool for suggesting code. GitHub Copilot can grasp the crucial details of your project through its training of data containing both natural language and billions of lines of source code from publicly available sources, including code in public GitHub repositories. This allows GitHub Copilot to provide you with more context-aware suggestions.

But to get the most out of GitHub Copilot, you need to know about prompting. This is the way you tell Copilot what you need. The quality of the code it gives back depends a lot on how clear and accurate your prompts are.

So how can you use GitHub Copilot to its full potential? This article will show you how! It guides you through the details of making effective prompts to get the best code suggestions, helping you code faster and better.

What is Prompt Engineering?

Prompt engineering is the process of creating clear instructions to guide AI systems, like GitHub Copilot, to generate context-appropriate code according to your project's specific needs. This ensures the code is syntactically, functionally, and contextually correct. Think of it like giving precise directions to a driver. Without them, the journey might be inefficient. But with clear guidance, the route becomes direct and efficient, saving time and energy. In this scenario, you're the one providing directions, and GitHub Copilot is your skilled driver, ready to drive you smoothly through your coding journey with the right guidance.

Now that you know what prompt engineering is, let's learn about some of its principles.

Principles of Prompt Engineering

Before we explore specific strategies, let's first understand the basic principles of prompt engineering, summed up in the 4 S's below. These core rules are the basis for creating effective prompts.

• Single: Always focus your prompt on a single, well-defined task or question. This clarity is crucial for eliciting accurate and useful responses from Copilot.
• Specific: Ensure that your instructions are explicit and detailed. Specificity leads to more applicable and precise code suggestions.
• Short: While being specific, keep prompts concise and to the point. This balance ensures clarity without overloading Copilot or complicating the interaction.
• Surround: Utilize descriptive filenames and keep related files open. This provides Copilot with rich context, leading to more tailored code suggestions.

Best practices in prompt engineering

• Understand your problem: Clearly define a problem that you are trying to solve. As Copilot is associated with code generation, it’s up to you to guide it in the right direction.
• Provide Clear Context: Give Copilot as much context as possible by writing clear comments and providing descriptive functions and variable names.
• Review and Refine: After providing as much context as possible it generates the output but it is to be considered as the starting point and then choose the way to review and refine it again to meet our required standards if required.
• Teach Copilot: If Copilot suggests something incorrect, take the time to correct it. This helps improve its suggestions for future use.
• Use with Caution: It generates code but goes ahead without any understanding and choosing a blind move over the generated code is not useful because it generally saves our time but choosing a way to understand it and correct it on your own.
• Pair Programming: Collaborate with Copilot like the collaboration with a human teammate. In general, discuss with each other and learn from each other.
• Test Extensively: Just like any code thoroughly test the code in the sense that every time check the code it generates and check the behaviour of it.
• Stay Legal: Ensure that you have the right to use any code it generates.
• Feedback Loop: Provide Feedback to GitHub about Copilot’s performance. This helps to improve its suggestions and provide the best result.
• Learn Continuously: Use Copilot as a learning tool. Analyze its suggestions to understand the different approaches and solutions to common programming problems.

How Copilot Learns from your Prompts?

GitHub Copilot operates based on AI models trained on vast amounts of data. To enhance its understanding of specific code contexts, engineers often provide it with examples. This practice, commonly found in machine learning, led to different training approaches such as:

Zero-shot learning

Here, GitHub Copilot generates code without any specific examples, relying solely on its foundational training. For instance, suppose you want to create a function to convert temperatures between Celsius and Fahrenheit. You can start by only writing a comment describing what you want, and Copilot might be able to generate the code for you, based on its previous training, without any other examples.

# I need a function to convert Celsius to Fahrenheit

def celsius_to_fahrenheit(celsius):
  
  fahrenheit = (celsius * 9/5) + 32
  return fahrenheit

One-shot learning

With this approach, a single example is given, aiding the model in generating a more context-aware response. Building upon the previous zero-shot example, you might provide an example of a temperature conversion function and then ask Copilot to create another similar function. Here's how it could look:

# Example: Function to convert Fahrenheit to Celsius
def fahrenheit_to_celsius(fahrenheit):
  celsius = (fahrenheit-32) * 5/9
  return celsius

# Now I need a function to convert Celsius to Fahrenheit

def celsius_to_fahrenheit(celsius):
  fahrenheit = celsius * 9/5 + 32
  return fahrenheit

Few-shot learning

In this method, Copilot is presented with several examples, which strike a balance between zero-shot unpredictability and the precision of fine-tuning. Let's say you want to generate code that sends you a greeting depending on the time of the day. Here's a few-shot version of that prompt:

# Example 1: Greeting message for morning
# Input: 9 AM
# Output: "Good morning!"

# Example 2: Greeting message for afternoon
# Input: 2 PM
# Output: "Good afternoon!"

# Example 3: Greeting message for evening
# Input : 7 PM
# Output : "Good evening!"

# Now, generate a python code that takes the current time as input using the datetime module
# and returns the appropriate greeting message

# Solution:
# Import datetime module
import datetime

# Get current time
current_time = datetime.datetime.now()

# Get current hour
current_hour = current_time.hour

# Check if it is morning (before 12 PM)
if current_hour < 12:
  print("Good morning!")
  
 # Check if it is afternoon (between 12 PM and 4 PM)
elif current_hour < 16:
  print("Good afternoon!")
  
 # Check if it is evening (after 4 PM)
elif current_hour < 21:
  print("Good evening!")

  # Else it is night time 
else:
  print("Good night!")

Let’s Consider a real-life Engineering problem:

Problem: You are developing a Web Application that requires user authentication. You need to implement a secure login system using JSON Web Tokens(JWT) in your Node.js backend.

Using GitHub Copilot:

1. Contextualize the Problem: In your Node.js codebase, create a new file named ‘auth.js’ where you will handle authentication-related functions.

2. Provide Contextual Comments: Add Comments explaining what you need, such as:

 // Function to generate JWT Token for user authentication

3. Invoke GitHub Copilot: Start writing the function signature or comment describing what you need, like:

 // Generate JWT token for user authentication

4. Review Copilot Suggestions: Copilot might suggest code like :

    const jwt = require('jsonwebtoken
function generateToken(payload, secret, options) {
       return jwt.sign(payload, secret, options);
}');

5. Refine the Suggestions: Ensure that the function meets your requirements and project conventions. To validate input parameters and handle errors:

const jwt = require('jsonwebtoken');
function generateToken(payload, secret, options) {
     if(!payload || !secret) {
        throw new Error('Payload and Secret are required');
     }
     return jwt.sign(payload, secret, options);
 }

6. Test the Function: Write test cases to ensure the function works as expected, considering different scenarios like valid and invalid input, expired tokens, etc.

7. Feedback Loop: If Copilot’s suggestions are not accurate or if you encounter any issues, provide feedback so that Copilot can improve its suggestions as well accordingly.

8. Continuously Improve: As you work on your project, continue using Copilot for other authentication-related functions, such as token verification, token expiration handling, and refresh token generation.

Conclusion

By following these steps, we can effectively make the GitHub Copilot assist with implementing secure authentication in your Node.js backend, saving time and reducing the chance of errors.