Golang错误链式返回实现详解

type ConfigBuilder struct {
    config map[string]string
    err    error
}

func NewConfigBuilder() *ConfigBuilder {
    return &ConfigBuilder{config: make(map[string]string)}
}

func (cb *ConfigBuilder) SetHost(host string) *ConfigBuilder {
    if cb.err != nil {
        return cb
    }
    if host == "" {
        cb.err = fmt.Errorf("host cannot be empty")
        return cb
    }
    cb.config["host"] = host
    return cb
}

func (cb *ConfigBuilder) SetPort(port int) *ConfigBuilder {
    if cb.err != nil {
        return cb
    }
    if port <= 0 {
        cb.err = fmt.Errorf("invalid port: %d", port)
        return cb
    }
    cb.config["port"] = strconv.Itoa(port)
    return cb
}

func (cb *ConfigBuilder) Build() (map[string]string, error) {
    if cb.err != nil {
        return nil, cb.err
    }
    // 深拷贝避免外部修改
    result := make(map[string]string)
    for k, v := range cb.config {
        result[k] = v
    }
    return result, nil
}

cfg, err := NewConfigBuilder().
    SetHost("localhost").
    SetPort(8080).
    Build()

if err != nil {
    log.Fatal(err)
}
fmt.Println(cfg)

type Step func() error

func RunSteps(steps ...Step) error {
    for _, step := range steps {
        if err := step(); err != nil {
            return err
        }
    }
    return nil
}

// 使用
err := RunSteps(
    func() error { return step1() },
    func() error { return step2() },
    func() error { return step3() },
)