闭包

# use std::thread;
# use std::time::Duration;
#
let expensive_closure = |num| {
       println!("calculating slowly..."); 
       thread::sleep(Duration::from_secs(2)); 
       num
};
# expensive_closure(5);

闭包的定义

• 以一对 | 开始
• 在|中间指定闭包的参数
• 如果有多个参数, 使用逗号分隔 |param1,param2|
• 闭包不要求像 fn 函数那样在参数和返回值上注明类型

self.containers
            .iter()
            .enumerate()
            .map(|(index,c)| core::Container {
                name: c.name.clone(),
                image: Some(c.image.clone()),
                image_pull_policy: Some("IfNotPresent".to_string()),
                resources: Some(c.resources.to_resource_requirements()),
                ports: Some(c.ports.iter().map(|p| p.to_container_port()).collect()),
                command: c.cmd.clone(),
                args: c.args.clone(),
                env: Some(
                    c.env
                        .iter()
                        .map(|e| e.to_env_var(resolved_vals.clone()))
                        .collect(),
                ),

                volume_mounts: c.volume_mounts(index,instance_name.clone()),
                liveness_probe: c.liveness_probe.clone().and_then(|p| Some(p.to_probe())),
                readiness_probe: c.readiness_probe.clone().and_then(|p| Some(p.to_probe())),
                ..Default::default()
            })
            .collect()