Function parameters in Lua allow you to pass data to functions, making them more flexible and reusable. Understanding how to work with parameters is crucial for writing efficient Lua code.

Basic Syntax

In Lua, function parameters are defined within parentheses after the function name. Here's the basic syntax:

function functionName(parameter1, parameter2, ...)
    -- Function body
end

Parameters act as local variables within the function scope. They receive values when the function is called.

Types of Parameters

1. Positional Parameters

The most common type of parameters in Lua. They are assigned values based on their position in the function call.

function greet(name, age)
    print("Hello, " .. name .. "! You are " .. age .. " years old.")
end

greet("Alice", 30)  -- Output: Hello, Alice! You are 30 years old.

2. Default Parameters

Lua doesn't have built-in default parameters, but you can simulate them using logical operators:

function greet(name, age)
    name = name or "Guest"
    age = age or "unknown age"
    print("Hello, " .. name .. "! You are " .. age .. ".")
end

greet()  -- Output: Hello, Guest! You are unknown age.

3. Variable Number of Arguments

Lua supports functions with a variable number of arguments using the ... syntax:

function sum(...)
    local total = 0
    for _, value in ipairs({...}) do
        total = total + value
    end
    return total
end

print(sum(1, 2, 3, 4))  -- Output: 10

Best Practices

Use descriptive parameter names to improve code readability.
Limit the number of parameters to maintain function simplicity.
Consider using tables for complex parameter sets.
Validate parameter types and values when necessary.

Related Concepts

To deepen your understanding of Lua functions and parameters, explore these related topics:

By mastering Lua function parameters, you'll be able to create more flexible and powerful functions in your Lua programs.