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#![cfg(feature = "embed")]
use magnus::{function, method, prelude::*};
/// Building on top of `wrap`, we can rely on Rust's enum to dispatch based on enum variants.
/// Magnus will transform the types between Ruby and Rust.
#[magnus::wrap(class = "Shape")]
enum Shape {
#[magnus(class = "Circle")]
Circle { radius: f64 },
#[magnus(class = "Rectangle")]
Rectangle { x: f64, y: f64 },
}
impl Shape {
fn new_circle(radius: f64) -> Self {
Self::Circle { radius }
}
fn new_rectangle(x: f64, y: f64) -> Self {
Self::Rectangle { x, y }
}
fn area(&self) -> f64 {
match self {
Shape::Circle { radius } => std::f64::consts::PI * radius * radius,
Shape::Rectangle { x, y } => x * y,
}
}
}
fn print_area(s: &Shape) {
println!("{}", s.area());
}
fn main() -> Result<(), String> {
// Normal Rust code
let a = Shape::Circle { radius: 10.0 };
let b = Shape::Rectangle { x: 10.0, y: 2.0 };
print_area(&a);
print_area(&b);
// magnus binding running in Ruby
magnus::Ruby::init(|ruby| {
let shape_class = ruby.define_class("Shape", ruby.class_object())?;
shape_class.undef_default_alloc_func();
// inherit from Shape
let circle_class = ruby.define_class("Circle", shape_class)?;
circle_class.define_singleton_method("new", function!(Shape::new_circle, 1))?;
circle_class.define_method("area", method!(Shape::area, 0))?;
let rectangle_class = ruby.define_class("Rectangle", shape_class)?;
rectangle_class.define_singleton_method("new", function!(Shape::new_rectangle, 2))?;
rectangle_class.define_method("area", method!(Shape::area, 0))?;
let d: f64 = ruby.eval(
"a = Circle.new(10.0)
b = Rectangle.new(10.0, 2.0)
difference = a.area - b.area
puts \"The difference of the area between the circle and the rectangle is #{difference}.\"
difference",
)?;
println!("{}", d);
Ok(())
})
}
|
