Skip to main content

Method overloads

Lua has no static types, so same-name multiple signatures cannot be chosen at compile time. ZLua provides: default dispatch, full-signature keys (automatic at Bind), [LuaAlias], and register_method short names. See: Demo.Run, app.lua.

Day-to-day demo:Run(10) is enough in Lua calling C#; read this page for ambiguity or hot paths. Authoritative details: Overload Spec.

How to choose​

ApproachSyntaxWhen
Default dispatchdemo:Run(10)Arguments uniquely match
Full-signature key (automatic)demo['Run(System.Int32)'](demo, 5)Exact pick; no register_method needed
[LuaAlias]demo:run_i32(5)You can edit C#; short name on hot paths
register_methodAfter register: demo:run_i32(5)Cannot edit C#; still want short name + colon

Default dispatch​

demo:Run(10)        -- Run(int)
demo:Run("hello")   -- Run(string)

Zero dispatch when there is only one public overload; with multiple, match by arguments.

Full-signature keys (auto-registered on name conflicts)​

When the same method name has multiple overloads (e.g. Run(int) / Run(string)), besides the Run dispatch, Bind also hangs a direct key for each candidate:

MethodName(parameter Type.FullName, …) (no return type):

KeyMeaning
RunRuntime dispatch
Run(System.Int32)Fixed Run(int)
Run(System.String)Fixed Run(string)
-- 精确调用，不必 register_method
demo['Run(System.Int32)'](demo, 5)
demo['Run(System.String)'](demo, "hi")

Keys contain parentheses, so you cannot write demo:Run(System.Int32)(...); use bracket keys + dot + explicit self.

[LuaAlias]​

[LuaAlias("run_i32")]
public void Run(int value) { }

public void Run(string value) { }
demo:run_i32(10)    -- 短名 + 冒号，O(1)；Run(int) 已换名，不再挂 "Run"
demo:Run("hi")      -- 未换名的 Run(string)

An alias is a rename (replaces the default Lua key), not an append. XML (luaAliasXmlPaths / ZLuaAlias) and more examples: LuaAlias. C# extensions on the instance table: Extension methods.

register_method: short name + colon​

Full-signature keys already allow exact calls, but the syntax is verbose. register_method hangs a direct closure onto an unused short name; then you can use colon:

local run_i32 = demo['Run(System.Int32)']
zlua.register_method("run_i32", run_i32)

-- 好处：短名进入 method 表，之后直接
demo:run_i32(5)

Two-argument form (per 05-LIB): zlua.register_method(aliasName, directClosure). If aliasName already exists (including Run, full-signature keys, other aliases) → error; no overwrite.

You can also take a closure from a [LuaAlias] key and hang another custom name.

Common mistakes​

SymptomFix
Wrong overload / ambiguous overloadFull-signature key, [LuaAlias], or register_method short name
Want demo['(System.Int32)']Forbidden; must include the method name: Run(System.Int32)
register_method says already takenPick an unused alias; do not overwrite Run / existing full-signature keys

Learning path​

Previous0GC Marshal
NextLuaAlias