Metaclass

Based on game build 714014 | Last updated: 2026-03-10

Overview

Metaclass implements a class factory that constructs classes backed by Lua userdata instead of plain tables. This design allows overriding critical metamethods such as __gc (garbage collection) and __len (length), which are otherwise unavailable for tables. It is an internal infrastructure utility used to build robust, garbage-collectable class instances with fine-grained control over core operations.

Usage example

local MyClass = MetaClass(nil, function(self, value)
    self.value = value
end)

local obj = MyClass(42)
print(obj.value)  -- 42
print(#obj)       -- uses __len if defined in class or base

Dependencies & tags

Components used: None identified
Tags: None identified

Properties

No public properties

Main functions

MetaClass(base, _ctor)

• Description: Constructs a new class using userdata as the underlying object type. Supports inheritance via base and custom construction via _ctor.
• Parameters:
  • base (table or nil) — optional parent class or table of methods to copy.
  • _ctor (function or nil) — optional constructor function called with (self, ...) when instantiating. If omitted and base is a function, base is treated as _ctor.
• Returns: (table) A class table that can be invoked as a constructor (e.g., MyClass(arg)).
• Error states: None — the function always returns a valid class table.

c.is_a(self, klass)

• Description: Checks if an instance self is of class klass or inherits from it (inclusive of inheritance chain via _base).
• Parameters:
  • self (userdata) — instance to test.
  • klass (table) — class (or base class) table to check against.
• Returns: (boolean) true if self is an instance of klass or descends from it; false otherwise.

Events & listeners

None identified