Lesson 21 of 55
9 mins readPython Variadic Functions & Variable Arguments (...)
In Plain English
Functions accepting variable arguments define `...` (three dots) in their parameter list. Access arguments using `table.pack(...)`, `select()`, or by collecting into a table `{ ... }`.
Deep Dive: How It Works
Ellipsis Parameter (...): Represents all passed extra arguments.
Table Packing: `local args = { ... }` or `local packed = table.pack(...)` (stores count in `packed.n`).
select(n, ...): Returns arguments starting from index `n`. `select("#", ...)` returns the total argument count.
Core Rules to Remember
Ellipsis (...) Notation: Captures arbitrary argument counts cleanly.
select("#", ...): Efficiently counts variable arguments without creating table allocations.
Live Interactive Example
Hit Run Code to see it liveSumming Arbitrary Numbers with Varargs
Python 3.12
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Output Console
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How it works: { ... } collected the variadic arguments into a table for iteration.
Your Turn: Micro Challenge
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Micro Exercise
Count Varargs with select
- Define `local function count_args(...) return select("#", ...) end`.
- Print `"Args count: " .. count_args("a", "b", "c", "d")`.
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Sandbox Output
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