NLua Examples

Demonstrations of integrating Lua scripting into C# applications using NLua for dynamic behavior without recompilation.

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Installation

Install NLua via NuGet:

Install-Package NLua -Version 1.5.1

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Overview

NLua enables C# applications to execute and interact with Lua scripts dynamically, allowing behavior changes without recompiling. This example demonstrates:

• Registering C# methods for Lua to call
• Executing Lua scripts from C#
• Retrieving variables from Lua back to C#

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Key Features

• Method Registration — Register C# functions as Lua callables
• Script Execution — Run Lua scripts within C# context
• Variable Retrieval — Access Lua variables from C#
• Dynamic Behavior — Modify logic via scripts without recompiling

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Example Code

Lua Initialization

Create a new Lua state:

var state = new Lua();

Register C# Methods for Lua

state["print"] = (Action<string>)LuaPrint;
state["magnitude"] = (Func<float, float, float>)CalculateMagnitude;

Execute Lua Script

Define and run Lua code:

function calculate()
    local result = magnitude(3.0, 4.0)
    print("Magnitude: " .. result)
end
calculate()

Access Lua Variables

Retrieve values from Lua:

var value = state["myVariable"];

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Project Structure

├── README.md
├── NLuaExamples.sln
└── src/
    ├── LuaInterop.cs         — Main Lua integration class
    ├── Examples.cs           — Example code demonstrating features
    └── LuaScripts/
        └── script.lua        — Sample Lua scripts

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Architecture

Lua State Management

• Single Lua instance per application context
• Method registration enables C# ↔ Lua communication
• Variable sharing through indexing (state["name"])

Type Conversion

NLua automatically converts between:

• C# methods → Lua functions
• Lua tables → C# dictionaries
• Lua numbers → C# float/double
• Lua strings → C# strings

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Common Patterns

Safe Script Execution

try
{
    state.DoString("-- Lua code here");
}
catch (Exception ex)
{
    Console.WriteLine("Lua error: " + ex.Message);
}

Callback Registration

state["onEvent"] = (Action<string>)HandleEvent;
// Call from Lua: onEvent("data")

Complex Data Exchange

// Set table from C#
state.DoString("data = {}");
state["data"] = new LuaTable(state);
state.DoString("table.insert(data, 'value')");

// Retrieve from Lua
var result = state["data"];

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Important Notes

• Wrap Lua execution in try-catch for error handling
• Ensure C# method signatures match Lua function expectations
• NLua handles type conversions between C# and Lua
• Keep Lua scripts simple for better performance
• Use LuaTable for structured data exchange