Not rewriting a method just to add a single line of code?

Question

Time and time again this has happened to me: We have class CLS with init method like this:

init {
    // do A

    // do B

    // do C
}

Now, in a certain case we need to do X exactly between B and C. Making a subclass of CLS and re-writing the whole init method with X inserted there does not seem like a good solution to me (It is the opposite of DRY), Is there a better solution that hasn't occurred to me?

Please note that A, B and C are small code fragments doing small tweaks like adjusting the UI so it is probably not a good idea to put them in separate methods. I'm currently coding in JavaScript but I think this question applies to other PLs as well.

Answer 1

We usually add hooks to the parent class, where we expect extensions. I don't remember what it is called though. Maybe it's the template method pattern?

class Foo {
  init() {
    console.log("A");
    console.log("B");
    this.doX();
    console.log("C");
  }
  doX(){}
}

class Bar extends Foo {
  doX() {
    console.log("X");
  }
}

new Bar().init();