3 Big, Scary Software Engineering Words Explained

Idempotent | Polymorphism | Isomorphic

A simple Google search often clarifies the meaning of unknown terms I encounter as a Software Engineer. Sometimes, though, they seem more complicated and require a second (or even third or fourth) look to understand them better.

We’ll cover three of these terms that have given me past trouble. I hope I can reduce your search just a smidge! 🙃

Here we’ll cover:

• What are these words?

• What do they mean to a Software Engineer?

• And what is an example to point to?

Let’s dive in!

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♻️ Idempotent

Simplified Meaning:

• The same result is produced every time an operation with a particular input is submitted as if it were only submitted once.

Use case:

• This typically refers to HTTP GET, PUT, or DELETE requests. This ensures reliability, consistency, and fault tolerance when working with a RESTful API.

  • GET is technically idempotent because it retrieves and does not change a resource.

• If the request is incomplete due to an error or issue, the client can resubmit the request to achieve the desired end result.

Example:

• A client submits a PUT request to change a user’s E164 format phone number from its original:

{
  "name": "Mindi",
  "email": "mindi@test.com",
  "phone": "+18885551234"
}

…to:

{
  "name": "Mindi",
  "email": "mindi@test.com",
  "phone": "+18885550001"
}

• If an unexpected error occurs at any level of the process, the client should be able to resubmit the request and expect the same result.

• No matter how often the client submits this exact PUT request, even if the user goes wild and submits 100 times, the E164 format phone number should ultimately reflect the desired update +18885550001.

Useful resources:

• Wikipedia

• MDN Web Docs

• REST API Tutorial: Idempotent REST API

• VIDEO: Alex Hyett

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🔀 Polymorphism

Simplified Meaning:

• Different objects can be treated as common, enabling the same operation to work uniquely on different objects.

• Ultimately, it refers to a programming aspect’s ability to appear similar but operate differently in certain scenarios.

Use case:

• Method overloading (see below example).

• Accept various function parameters.

  • For instance, if a function can accept an id that is either an integer or a string and operate upon it properly after determining which it has received.

• In my research, this can also apply to things like TypeScript types and interfaces.

• Using shared, common functionality allows for more flexible, scalable, and maintainable code long-term.

A common use of polymorphism in OOP is when a parent class reference is used to refer to a child class object. - Margaret Rouse, Techopedia

Example:

• Here, let’s do something simple. We’ll use Python to make a base Animal class and Dog and Cat derived classes to overwrite a core Animal class method.

class Animal:
  def sound(self):
    return "Each animal makes a unique sound!"

class Dog(Animal):
  def sound(self):
    return "woof woof"

class Cat(Animal):
  def sound(self):
    return "meow meow"

• When we create a function that can use any of these classes, we will see that an extensible class allows us to get the expected output from our cat or dog.

def animal_sound(critter):
    print(critter.sound())

# Create instances of Dog and Cat
dog = Dog()
cat = Cat()

# Call the animal_sound function with different types of animals
animal_sound(dog)  # Outputs: woof woof
animal_sound(cat)  # Outputs: meow meow

Useful resources:

• Wikipedia

• Techopedia

• Tech Target

• VIDEO: iAmDev

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💻 Isomorphic [JavaScript]

Simplified Meaning:

• JS code is written strategically to run on the client OR the server.

  • The project must maintain a minimum Node version and work on multiple browsers. Transpilers and polyfill tools implement modern JS features that may be missing, making this challenge a little easier!

  • Typically, you will use third-party libraries when writing your JS code and avoid using native Node libraries or browser APIs.

• General isomorphism in programming is slightly different (Stack Overflow link, for edification).

  • This is when different programming structures/processes can be transformed into one another without losing info or functionality. They are essentially the same in structure or behavior but may look different.

Use case:

• A file or code snippet that can be run in either instance, improving modularity.

• A project using server-side rendering to increase app performance.

  • This isn’t magic - there may be other performance drawbacks.

  • This can also provide crawlers access to content to improve SEO.

• Reduce discrepancies and potential bugs with consistent logic and rendering.

Example:

• Let’s do something super simple. We’ll create a snippet to inform you which environment is running.

// isomorphic.js

const defineEnvironment = () => {
  if (typeof window == 'undefined') {
    console.log('This is the server!')
  } else {
    console.log('This is the browser!')
  }
}

defineEnvironment()

• To run this in Node:

  • save the code

  • navigate to the file via a terminal or command prompt

  • run the script: node isomorphic.js

  • you should see “This is the server!”

• To run this in the browser:

  • open a browser’s dev tools

    • Google Chrome on a Mac = command + option + J

  • navigate to the console

  • paste the content of the isomorphic.js file into the console and run it

  • you should see “This is the browser!”

Useful resources:

• Wikipedia

• Medium Article from AirbnbEng

• GitHub repo examples

  • I have not vetted these, but they seem interesting!

• VIDEO: PortEXE

Do you feel at least slightly more confident with these words now?

I sure hope so! 🤭

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Thanks for reading! Did I miss anything, or would you like to add anything? Let me know! I appreciate constructive feedback so we can all learn together. 🙌