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Foundations
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Control Flow
If elseif While loop Repeat until Numeric for Generic for Break Goto labels Do blocks
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Function definitions Local functions Multiple returns Varargs First-class functions Closures Tail calls Self parameter colon syntax
Tables
Table literals Array-style tables Key-value tables Mixed tables Table.insert Table.remove Table.concat Table.sort
Metatables
Setmetatable __index __newindex __tostring __add __eq __len Rawget rawset
Iterators and Coroutines
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Modules and Environments
Require Package.path Module return table Local module state _ENV Load Loadfile Dofile
Strings and Patterns
String.find String.match String.gmatch String.gsub Pattern classes Captures Frontier patterns Balanced patterns
Files and Errors
Io.open File read File write Io.lines Error Assert Pcall Xpcall
Advanced Lua
Weak tables Garbage collection Table.pack unpack Utf8 library Os.date Math.random Debug traceback C API concept
Lua / Files and Errors

Error

Learn error in Lua through a focused explanation, a dedicated topic-specific example, an engineering boundary, and a mastery check.

12 min read • Advanced

error is an atomic Lua topic inside Files and Errors. The example uses the named construct directly so you can see its syntax, data flow, and observable behavior.

Read the code by locating the exact feature named error, then trace the value before and after that feature runs. This lesson is intentionally isolated from neighboring topics: changing identifiers alone would not reproduce the same behavior because the construct itself is different.

Topic-specific example

lua-0069-d092aaca05.lua
lua Try It Live 
local ok,msg=pcall(function()error("bad input")end);print(ok,msg:match("bad input"))
Edge case / engineering note

For error, test the boundary that makes the feature meaningful: invalid input, an empty value, a missing branch, lifecycle/cleanup, or a type/runtime constraint. Do not infer correctness only from the happy path.

Content source & attribution
Original Syntaxis Content · Original Syntaxis Content

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