Type system overview

:::tip Who should read this Developers already accessing C# from Lua who need to understand the CSharp table structure and static/instance isolation. Intro syntax: Lua accessing C# basics; API lookup: CSharp root table reference. :::

Design goals

Goal	Notes
Unified entry	All types lazy-load through the `CSharp` root table
Semantics close to C#	`Type()` construct, `obj:Method()`, `Type.Static()`
Static/instance isolation	Static and instance members use separate metadata tables
Public only	Lua can only access public members
Optimizable	Il2Cpp fields / no-arg properties can take fast paths

CSharp table structure

CSharp                          -- global root table
  └─ {assemblyName}             -- assembly table (e.g. Assembly-CSharp)
       └─ {typeFullName}        -- type table (bracket key when namespaced)
            ├─ static methodTable / fieldGetter / fieldSetter
            ├─ _ctor / __call   -- construct
            └─ __instance_mt    -- points at instance metatable template

Assembly alias (Demo convention):

CSharp['AC'] = CSharp['Assembly-CSharp']
local demo = CSharp.AC.Demo()

Static/instance isolation

Static and instance members must not be mixed:

Operation	Correct	Wrong
Static method	`CSharp.AC.Demo.Add(1, 2)`	`demo.Add(1, 2)`
Instance method	`demo:GetX()`	`CSharp.AC.Demo.GetX()`
Static field	`CSharp.AC.Demo.s_x = 1`	`demo.s_x = 1`

:::info Exception Static and instance use separate tables; generally no mixing. To precisely name a static overload, use the full-signature key on the type table, e.g. Demo['Add(System.Int32,System.Int32)'](1, 2). :::

Lazy load & EnsureBinding

On first access to a type, the runtime scans public members and fills the three tables:

Il2Cpp: Generate stubs + lazy bind; Mono: Expression Emit + lazy bind.

Namespaces & generics (summary)

Scenario	Syntax
No namespace	`CSharp.AC.Demo`
With namespace	`CSharp.AC['MyGame.UI.Panel']`
Open generic	`CSharp.mscorlib['System.Collections.Generic.List`1']`
Closed generic	`zlua.make_generic_type(ListDef, zlua.types.int32)`

Details: Generics & arrays Guide.

When to read the Spec

Question	Doc
How are members dispatched?	Metatable model
Overloads & aliases?	Method overload Spec
Arrays / inheritance?	Type system Spec

Design goals​

CSharp table structure​

Static/instance isolation​

Lazy load & EnsureBinding​

Namespaces & generics (summary)​

When to read the Spec​

Related​