And you might want to be very, very positive earlier than you resolve that there will be not more than three of something in your system. A corollary to this rule is…

Don’t hard-code something

This appears apparent, however some builders like to hard-code stuff. Candy child Elvis, I even see this sort of factor on a regular basis:

someString.PadLeft(13);

I imply, actually? Why 13? Why not 14? Or 12? How a couple of fixed that explains the which means of the worth?

You could not assume so, however each time you create an object inside a category, you might be hard-coding that class and its implementation. For instance:

class SimpleEncryptor {
  public encrypt(plainText: string): string {
    const weakEncryption = new WeakEncryptionAlgorithm();
    return weakEncryption.encrypt(plainText);
  }
}

So what if you wish to change the encryption algorithm? 

As an alternative, use dependency injection, and you need to use any algorithm you need:

interface IEncryptionAlgorithm {
  encrypt(plainText: string): string;
}

class SimpleEncryptor {
  public encrypt(plainText: string, encryptionAlgorithm: IEncryptionAlgorithm): string {
    return encryptionAlgorithm.encrypt(plainText);
  }
}

Typically ‘over-engineering’ is correct engineering

Imagine me, I get the notion of over-engineering. I simply informed you to maintain issues easy. However generally, doing issues “the appropriate manner” appears like over-engineering. Everytime you assume you might be over-engineering, cease and take into account that, properly, perhaps you aren’t. Creating interfaces and coding in opposition to them can seem to be over-engineering. I do know it’s a wonderful line to stroll, however planning forward for one thing you realize you’ll need will not be improper. And this leads me to…

Generally you will want it

I’ve by no means fairly understood the YAGNI precept (“You aren’t gonna want it”). All too usually, you discover that, properly, you realize, you probably did find yourself needing it. And by then, implementing this factor you “weren’t going to want” has turn out to be such a nightmare that you just dearly want you had gone forward an laid the groundwork for it. 

Possibly you hard-coded one thing (you weren’t going to want flexibility right here, proper?). Possibly you didn’t plan on ever needing seven taxes, or a distinct encryption algorithm. I see no hurt in pondering “You understand, finally, we’re going to have to take care of greater than widgets right here” and coding in order that adjustments are simple when new cogs and sprockets inevitably come alongside.