Discussion on: Is “Defensive Programming” actually healthy?

[Mazen Touati]

As I mentioned I was talking In General.

1) The if part: I meant making an early decisions may add more flexibility to your code for example

// You may use this
() => {
  if (condition1) {
    return 1;
  }

  // Maybe another logic in between

  if (condition2) {
    return 2;
  }

  return default;
}

// Instead of this
() => {
  if (condition1) {
    return 1;
  } else if (condition2) {
    return 2;
  } else {
    return default;
  }
}

Usually, it would make the code more readable and maintainable.

2) Well, my statement regarding the run-time exception was a little bit biased by the Open-Closed Principal as I mentioned. Which suggests making the code extensible without actually changing the base code itself.
Another reasons I was thinking about:

• Not all languages are compiled.
• May be another developer or team ( That happens he/it is not a big fan of Typescript ) try to use the JavaScript version of your code.
• In some cases may be the user try to maliciously change the values (for example your are expecting values from a predefined select menu => the user may alter the values before sending them). As I said earlier it's a personal taste and not related exactly to your specific example.

3) I think that we have to be creative about this point, making an application that is tolerant to run-time errors is always challenging and great (Maybe for your example, you can use the previous state as a fallback when a signal is not defined or maybe you can define an emergency safe state that avoids all damage maybe a pull-over state ). Also, it totally depends on the situation for uses cases with low tolerance to errors your approach may be appropriate for extent ( still you are not dealing with unexpected run-time errors ).

I hope that you got what I'm trying to illustrate.