35 lines
1.0 KiB
Rust
35 lines
1.0 KiB
Rust
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//! This example stores a Rhai closure for later use as a callback.
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use rhai::{Engine, EvalAltResult, FnPtr};
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fn main() -> Result<(), Box<EvalAltResult>> {
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// This script creates a closure which may capture variables.
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let script = "
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let x = 20;
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// The following closure captures 'x'
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return |a, b| (x + a) * b;
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";
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// To call a Rhai closure at a later time, you'd need three things:
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// 1) an `Engine` (with all needed functions registered),
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// 2) a compiled `AST`,
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// 3) the closure (of type `FnPtr`).
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let engine = Engine::new();
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let ast = engine.compile(script)?;
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let closure = engine.eval_ast::<FnPtr>(&ast)?;
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// Create a closure that we can call any time, encapsulating the
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// `Engine`, `AST` and `FnPtr`.
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let func = move |x: i64, y: i64| -> Result<i64, _> { closure.call(&engine, &ast, (x, y)) };
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// Now we can call `func` anywhere just like a normal function!
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let result = func(1, 2)?;
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println!("The Answer: {}", result); // prints 42
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Ok(())
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}
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