reorganize module

_archive/rhai_engine/rhaiexamples/callback.rs

@@ -0,0 +1,42 @@
+//! This example stores a Rhai closure for later use as a callback.
+
+use rhai::{Engine, EvalAltResult, FnPtr};
+
+// To call a Rhai closure at a later time, you'd need three things:
+// 1) an `Engine` (with all needed functions registered),
+// 2) a compiled `AST`,
+// 3) the closure (of type `FnPtr`).
+fn main() -> Result<(), Box<EvalAltResult>> {
+    let engine = Engine::new();
+
+    // This script creates a closure which captures a variable and returns it.
+    let ast = engine.compile(
+        "
+            let x = 18;
+
+            // The following closure captures 'x'
+            return |a, b| {
+                x += 1;         // x is incremented each time
+                (x + a) * b
+            };
+        ",
+    )?;
+
+    let closure = engine.eval_ast::<FnPtr>(&ast)?;
+
+    // Create a closure by encapsulating the `Engine`, `AST` and `FnPtr`.
+    // In a real application, you'd be handling errors.
+    let func = move |x: i64, y: i64| -> i64 { closure.call(&engine, &ast, (x, y)).unwrap() };
+
+    // Now we can call `func` anywhere just like a normal function!
+    let r1 = func(1, 2);
+
+    // Notice that each call to `func` returns a different value
+    // because the captured `x` is always changing!
+    let r2 = func(1, 2);
+    let r3 = func(1, 2);
+
+    println!("The Answers: {r1}, {r2}, {r3}"); // prints 40, 42, 44
+
+    Ok(())
+}