Example accessing enum companion

[som-snytt]

Fixes #11249

[som-snytt]

For "future reference", so to speak.

object ExoPlanetaryData:
  final val VulcanMass   = 5.331e+24
  final val VulcanRadius = 6.15297e6
import ExoPlanetaryData.*

import Planet.{VenusMass as VM, *}
enum Planet(mass: Double, radius: Double):
  private final val (MercuryMass @ _, MercuryRadius @ _) = (3.303e+23, 2.4397e6)

  case Mercury extends Planet(MercuryMass, MercuryRadius)             // Not found
  case Venus   extends Planet(VM, VenusRadius)                        // illegal reference
  case Earth   extends Planet(Planet.EarthMass, Planet.EarthRadius)   // ok
  case Vulcan  extends Planet(VulcanMass, VulcanRadius)               // ok
object Planet:
  private final val (VenusMass @ _, VenusRadius @ _) = (4.869e+24, 6.0518e6)
  private final val (EarthMass @ _, EarthRadius @ _) = (5.976e+24, 6.37814e6)
end Planet

[bishabosha]

@som-snytt please would you be able to check the commit I pushed?

[som-snytt]

@bishabosha I see you replaced royal "we"? I assumed you were required to use "royal we" as a condition of citizenship. But I am not bound to convention.

[bishabosha]

I see you replaced royal "we"? I assumed you were required to use "royal we" as a condition of citizenship. But I am not bound to convention.

I've noticed I have actually already used "we" in some other parts of this document (like for deprecation of enum cases) 😂

[som-snytt]

I will leave it to your discretion.

I recently joked that so-and-so should just change their pronouns to "we". I've forgotten the context, as one ought to do when there is no implicit context.

Edit: OK, now I see that the other usage of "we" is actually a deflection: No one wishes to be responsible for demoting Pluto, so it is natural to spread or diffuse the blame among the group.

[oscar-broman]

Is it really necessary to use that pattern matching syntax? The example would look a bit simpler if the names started with lowercase letters.

I'm just thinking it might confuse novices reading the documentation, especially since enums is a simple concept that people will want to learn initially as they learn a new language.

[som-snytt]

@oscar-broman I don't mind following up if you suggest a delta. I'm not sure what you mean, as it has been a few months.

I'm not sure the text is intended for novices? I mean, I can barely follow it.

[oscar-broman]

I just meant the example could look like this instead:

  import Planet.*
  enum Planet(mass: Double, radius: Double):
    private final val (mercuryMass, mercuryRadius) = (3.303e+23, 2.4397e6)

    case Mercury extends Planet(mercuryMass, mercuryRadius)             // Not found
    case Venus   extends Planet(venusMass, venusRadius)                 // illegal reference
    case Earth   extends Planet(Planet.earthMass, Planet.earthRadius)   // ok
  object Planet:
    private final val (venusMass, venusRadius) = (4.869e+24, 6.0518e6)
    private final val (earthMass, earthRadius) = (5.976e+24, 6.37814e6)
  end Planet

[bishabosha]

I'll open a PR

[som-snytt]

@oscar-broman Thanks for clarifying. The syntax was "pedagogical" because normally we expect "constants" to be uppercase. The idiom shown is how to achieve that.

[som-snytt]

@bishabosha I'm agnostic as to whether the example is done the right way or the wrong way. :)

[bishabosha]

see #14556