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Lua error and assert

Lua reference for lua error and assert.

Syntax

assert(type(id) == "number", "id must be a number")
if not ready then error("Not ready") end

Examples

Lua error and assert example

A focused example you can adapt while practising.

assert(type(id) == "number", "id must be a number")
if not ready then error("Not ready") end

Best practices

Start with the smallest working example, then adapt it to your project.
Use the language’s standard library and idioms before introducing extra dependencies.

At a glance

Purpose: Lightweight scripting and embedding
File extension: .lua
Runs in: Lua interpreter or a host application
Usually used with: Host APIs and Lua modules

Specifications & further reading

Lua reference manuals

Related Lua documentation

Lua Functions & Closures
Functions are first-class values in Lua: they can be stored, passed, and returned. A nested function can close over a local variable from its surrounding scope.Lua function declarations
Lua reference for lua function declarations.Lua multiple return values
Lua reference for lua multiple return values.Lua closures
Lua reference for lua closures.