如何在Rust中实现在运行时选择的策略？

trait Strategy {
    fn execute(&self);
}

struct StrategyA;
impl Strategy for StrategyA {
    fn execute(&self) {
        println!("Executing strategy A");
    }
}

struct StrategyB;
impl Strategy for StrategyB {
    fn execute(&self) {
        println!("Executing strategy B");
    }
}

struct Context {
    strategy: Box<dyn Strategy>,
}

impl Context {
    fn new(strategy: Box<dyn Strategy>) -> Self {
        Context { strategy }
    }

    fn set_strategy(&mut self, strategy: Box<dyn Strategy>) {
        self.strategy = strategy;
    }

    fn execute_strategy(&self) {
        self.strategy.execute();
    }
}

fn main() {
    let strategy_a = Box::new(StrategyA);
    let strategy_b = Box::new(StrategyB);

    let mut context = Context::new(strategy_a);
    context.execute_strategy();

    context.set_strategy(strategy_b);
    context.execute_strategy();
}