Modules

Use this when you want a reusable object without a tagged Script.

Untagged .cpp = ModuleScript

src/ReplicatedStorage/Shared/Utils/Coins.clp

#include <clpp/roblox.clh>

int DoubleCoins(int coins) {
  return coins;
}

out/ReplicatedStorage/Shared/Utils/Coins.luau   -- ModuleScript, exported functions

Quoted #include "TemplateData.hpp" is not inlined when the header has a sibling .cpp or is a shared module: cluaupp build emits require(ReplicatedStorage.Cluaupp.constants.TemplateData) / require(ServerScriptService.Cluaupp.configurations.PlayerDataVersion) (Rojo roots from default.project.json), never script.Parent.Parent.shared.

.clh are type modules. A service header becomes export type Name = { init: (self: Name) -> (), … } and a typed table. The sibling .cpp is the construction (NameImpl.luau); the header requires that impl and binds the functions. Data-only structs still emit a constructor so TemplateData() works. Untagged .cpp without a header is a ModuleScript other Luau can require. Prefer headers for the public type, tagged .server.clpp / .client.clpp for scripts, and the sibling .clp / .clpp for method bodies.

Structs = data, not classes

The subset allows structs for IntelliSense and designated initializers (tables):

struct TemplateData {
  struct Currencies {
    int Money = 0;
    int Level = 1;
  } Currencies;
};

TemplateData playerData = TemplateData {};

That is your “class fields”. Methods are named functions next to them (EnsureStat, ApplyCurrencies). Cluaupp does not emit function TemplateData:GetMoney().

Methods as functions

void EnsureStat(Folder folder, string name, int value) {
  auto stat = folder.FindFirstChild(name);
  if (stat == null) {
    post("EnsureStat: " .: name .: " not found");
    return;
  }
}

Pass the instance in (folder, player). That is composition: the Folder is the object, the function is the method.

Janitor as the destructor

There is no C++ destructor. Pair “construct” with a Janitor:

auto janitor = new Janitor();
janitor.LinkToInstance(player);
janitor.Add(player.AncestryChanged~>Connect(OnAncestry));

When the player leaves, LinkToInstance runs Cleanup. That is RAII for Roblox.

Start / Stop

On generated services, Main.Start / Main.Stop are the constructor / destructor of the system. Put connections in Start (or in init() / PlayersManager). Do not leak Connect without a Janitor.

What not to write

class Shop {
  int price;
  void Buy(Player player);
};

Custom classes are not supported. Split into a struct (fields) + functions (methods) + a .server.clpp or untagged module (lifetime).