[vips7L]

With proper OO you could still implement that on the user object.

    boolean isAdult() {
        return this.age >= this.location.ageOfAdulthood();

        // or this.location.isAdult(this.age);  pick your poison!
    }

…anyway it’s just an example of how to introduce OO concepts. As everything in programming it depends

[Terr_]

Just having some fun with bikeshedding here: Yeah, that could work but IMO in a big/international system the responsibility should ideally live elsewhere, since:

* You may need to determine adulthood for a different jurisdiction than where the person currently resides. Their citizenship may be elsewhere, or you may be running a report that expects "adulthood" to be by some other region's standards, etc.

* Sometimes the underlying kind of adult-need wanted is slightly different, like for consuming alcohol or voting.

* There may be a weird country or province has laws that need additional factors, like some odd place where it's a different age-cutoff for men and women.

[vips7L]

Yes this is just extreme bike-shedding at this point. But none of this is impossible with more OO principles, like interfaces:

    class User {
        // Convenience function to check if the user is an adult in their current location
        boolean isAdult() {
            return this.location.isAdult(this);
        }


        boolean isOfDrinkingAge() {
            return this.location.isOfDrinkingAge(this);
        }
    }

    interface Location {
        boolean isAdult(User u);
        boolean isOfDrinkingAge(User u);
    }

    class WeirdLawsLocation implements Location {
        boolean isAdult(User u) {
            return switch (u.gender()) {
                case MALE -> u.age() >= 16;
                case FEMALE -> u.age() >= 18;
            }     
        }

        boolean isOfDrinkingAge(User u) {
            return u.age() >= 21
        } 
    }

In the hypothetical that you want to check somewhere the user is not currently:

    class SwedenLocation implements Location {
        boolean isAdult(User u) {
            return u.age() >= 18;
        }

        boolean isOfDrinkinAge(User u) {
            return u.age() >= 18;
        }
    }
    var sweden = new SwedenLocation();
    sweden.isOfDrinkingAge(user);

[Terr_]

That feels like unnecessary levels of indirection to provide a method that shouldn't be on the User anyway.

    j = Jurisdiction.fromUserLocation(user);
    j.isOfDrinkingAge(user);

[vips7L]

> that shouldn't be on the User anyway.

That’s just your opinion. It’s ok to provide convenience functions. I see no difference between the amount of indirection in our implementations, except mine is in the more natural place and you don’t have to know how to get a location or jurisdiction to answer the question: “is this user an adult?”. Knowing that it uses a location or jurisdiction is an implementation detail that you shouldn’t couple yourself to.

Cheers mate, I think I’m done moving goal posts for this conversation :)

[vips7L]

On a side note, this discussion really made me realize how useful concise method bodies would be in Java: https://openjdk.org/jeps/8209434

[ahoka]

Wow, thanks for proving that OOP was a mistake.

[vips7L]

I challenge you to do it better then.

Also from the guidelines:

> Please don't post shallow dismissals, especially of other people's work. A good critical comment teaches us something.