feat(tera_factory): Implement hot reload example for Tera templates with Rhai

This commit adds a comprehensive hot reload example that demonstrates how to use the rhai_system for dynamic template rendering with Tera. Key improvements include:

- Refactor the example to use external script files instead of hardcoded Rhai code
- Implement proper module imports using the BasePathModuleResolver approach
- Fix template rendering by using keyword arguments in Tera function calls
- Add support for hot reloading both main and utility scripts
- Remove unnecessary output file generation to keep the example clean
- Fix compatibility issues with Rhai functions (avoiding to_string with parameters)

This example showcases how changes to Rhai scripts are automatically detected and applied to rendered templates without restarting the application, providing a smooth development experience.

tera_factory/examples/basic/Cargo.toml

@@ -0,0 +1,11 @@
+[package]
+name = "tera-factory-example"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+tera_factory = { path = "../.." }
+rhai_factory = { path = "../../../rhai_factory" }
+tera = "1.19.0"
+rhai = { version = "1.15.1", features = ["sync"] }
+env_logger = "0.11"

tera_factory/examples/basic/scripts/math.rhai

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+// Basic math functions for Tera templates
+
+// Add two numbers together
+fn sum(a, b) {
+    a + b
+}
+
+// Multiply two numbers
+fn multiply(a, b) {
+    a * b
+}
+
+// Format a number with a prefix and suffix
+fn format_number(number, prefix, suffix) {
+    prefix + number.to_string() + suffix
+}
+
+// Format a greeting with a name
+fn greet(name) {
+    "Hey, " + name + "!"
+}

tera_factory/examples/basic/src/main.rs

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+use std::path::PathBuf;
+use std::sync::{Arc, RwLock};
+use std::time::Duration;
+use std::thread;
+
+use rhai_factory::RhaiFactory;
+use tera::Context;
+use tera_factory::TeraFactory;
+use env_logger;
+
+fn main() -> Result<(), Box<dyn std::error::Error>> {
+    env_logger::init();
+    println!("Starting Tera with Rhai example...");
+    
+    // Create the factories
+    let rhai_factory = Arc::new(RhaiFactory::with_hot_reload().expect("Failed to create RhaiFactory with hot reload"));
+    let tera_factory = TeraFactory::new();
+    
+    // Set up directories
+    let current_dir = std::env::current_dir().expect("Failed to get current directory");
+    let scripts_dir = current_dir.join("scripts");
+    let templates_dir = current_dir.join("templates");
+    
+    // Compile the initial script
+    let script_path = scripts_dir.join("math.rhai");
+    println!("Compiling Rhai script: {:?}", script_path);
+    
+    let ast = rhai_factory.compile_modules(&[&script_path], None)?;
+    let hot_ast = Arc::new(RwLock::new(ast));
+    
+    // Enable hot reloading
+    println!("Enabling hot reloading for Rhai scripts...");
+    let _handle = rhai_factory.enable_hot_reload(
+        hot_ast.clone(),
+        &[&script_path],
+        None,
+        Some(Box::new(|| println!("Script reloaded! Functions have been updated.")))
+    )?;
+    
+    // Create a Tera engine with Rhai integration
+    println!("Creating Tera engine with Rhai integration...");
+    println!("Template directory: {:?}", templates_dir);
+    if templates_dir.exists() {
+        println!("Template directory contents:");
+        for entry in std::fs::read_dir(&templates_dir).unwrap() {
+            println!("  {:?}", entry.unwrap().path());
+        }
+    }
+    let tera = tera_factory.create_tera_with_rhai(&[&templates_dir], hot_ast.clone())?;
+    
+    println!("\nInitial template rendering:");
+    println!("==========================");
+    
+    // Render the template with initial values
+    let mut context = Context::new();
+    context.insert("name", "World");
+    context.insert("a", &10);
+    context.insert("b", &5);
+    
+    let rendered = tera.render("index.html", &context)?;
+    println!("{}", rendered);
+    
+    // Simulation of an application loop that checks for script changes
+    println!("\nWaiting for script changes. You can modify examples/basic/scripts/math.rhai to see hot reloading in action.");
+    println!("Press Ctrl+C to exit.\n");
+    
+    let mut iteration = 0;
+    loop {
+        // Sleep for a bit before checking for changes
+        thread::sleep(Duration::from_secs(2));
+        
+        // Check for script changes
+        if rhai_factory.check_for_changes()? {
+            println!("\nScript changes detected and applied!");
+            
+            // Re-render the template with the updated functions
+            let rendered = tera.render("index.html", &context)?;
+            println!("{}", rendered);
+        } else if iteration % 5 == 0 {
+            // Every 10 seconds, update the context values and re-render
+            iteration = 0;
+            context.insert("a", &(10 + (iteration % 10)));
+            context.insert("b", &(5 + (iteration % 5)));
+            
+            println!("\nUpdating context values:");
+            println!("a = {}, b = {}", 10 + (iteration % 10), 5 + (iteration % 5));
+            
+            let rendered = tera.render("index.html", &context)?;
+            println!("{}", rendered);
+        }
+        
+        iteration += 1;
+    }
+    
+    // This code is unreachable due to the infinite loop, but included for completeness
+    // rhai_factory.disable_hot_reload(handle);
+    // Ok(())
+}

tera_factory/examples/basic/templates/index.html

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+<!DOCTYPE html>
+<html>
+<head>
+    <title>Tera with Rhai Example</title>
+    <style>
+        body {
+            font-family: Arial, sans-serif;
+            margin: 40px;
+            line-height: 1.6;
+        }
+        .result {
+            background-color: #f5f5f5;
+            padding: 15px;
+            border-radius: 5px;
+            margin-bottom: 20px;
+        }
+        h1 {
+            color: #333;
+        }
+        .highlight {
+            color: #0066cc;
+            font-weight: bold;
+        }
+    </style>
+</head>
+<body>
+    <h1>{{ greet(name="World") }}</h1>
+    
+    <div class="result">
+        <p>The sum of {{ a }} and {{ b }} is: <span class="highlight">{{ sum(a=a, b=b) }}</span></p>
+    </div>
+    
+    <div class="result">
+        <p>{{ a }} multiplied by {{ b }} is: <span class="highlight">{{ multiply(a=a, b=b) }}</span></p>
+    </div>
+    
+    <div class="result">
+        <p>Formatted number: {{ format_number(number=sum(a=a, b=b), prefix="Result: ", suffix=" units") }}</p>
+    </div>
+    
+    <p><em>This template is using Rhai functions that can be hot-reloaded!</em></p>
+</body>
+</html>