Go語言中處理可選參數(shù)主要有三種方式：?使用變參處理簡單情況，?使用配置結(jié)構(gòu)體處理多類型可選參數(shù)，?使用函數(shù)式選項處理高度可配置的API。對於順序敏感且類型相同的可選參數(shù)，可通過變參實現(xiàn)；當(dāng)參數(shù)較多或類型不同時，使用配置結(jié)構(gòu)體更清晰；對於需擴(kuò)展性強(qiáng)的庫或API，則推薦函數(shù)式選項模式，根據(jù)具體場景選擇合適的方式以保持代碼可讀性和一致性。

In Go, handling optional parameters isn't as straightforward as in some other languages that directly support default or named parameters. Since Go doesn't have built-in support for optional function parameters, developers typically use a few well-established patterns to achieve similar behavior.

Use Variadic Parameters for Simple Cases

One idiomatic approach is using variadic parameters when the optional values are all of the same type and order matters. This is often used when you expect zero or more values of the same kind.

For example:

 func sendNotification(message string, codes ...int) {
    status := 200
    if len(codes) > 0 {
        status = codes[0]
    }
    fmt.Printf("Message: %s, Status: %d\n", message, status)
}

You can call it like this:

 sendNotification("User logged in")
sendNotification("Error occurred", 500)

This works well when there's only one or two optional parameters and their meaning doesn't need explanation just by looking at the call site.

Use a Config Struct for Multiple Options

When your function requires multiple optional parameters (especially of different types), the preferred way is to define a config struct. Users can then provide only the fields they care about, while the function applies defaults for the rest.

Example:

 type RequestOptions struct {
    Timeout time.Duration
    Retries int
    AuthToken string
}

func sendRequest(url string, opts RequestOptions) {
    // Set defaults if not provided
    if opts.Timeout == 0 {
        opts.Timeout = 5 * time.Second
    }
    if opts.Retries == 0 {
        opts.Retries = 3
    }

    // Use opts fields...
}

Usage:

 sendRequest("/api/data", RequestOptions{
    Timeout: 10 * time.Second,
    Retries: 2,
})

This makes the API clean and self-documenting. It also allows adding new options later without breaking existing calls.

Consider Functional Options for Advanced Flexibility

For highly configurable APIs—especially those intended for libraries—the functional options pattern is widely adopted. It involves passing functions that modify an internal configuration.

Here's how it looks:

 type ClientOptions struct {
    retries int
    timeout time.Duration
    logger func(string)
}

type Option func(*ClientOptions)

func WithRetries(n int) Option {
    return func(c *ClientOptions) {
        c.retries = n
    }
}

func WithTimeout(d time.Duration) Option {
    return func(c *ClientOptions) {
        c.timeout = d
    }
}

func NewClient(opts ...Option) *Client {
    options := &ClientOptions{
        retries: 3,
        timeout: 5 * time.Second,
    }

    for _, opt := range opts {
        opt(options)
    }

    return &Client{options}
}

Usage:

 client := NewClient(WithRetries(5), WithTimeout(10*time.Second))

This pattern gives you flexibility and readability, especially when building complex APIs or libraries where extensibility matters.

These approaches are considered idiomatic in Go and are widely used across standard libraries and popular packages. Which one to choose depends on your specific use case:

• ? Use variadic args for simple optional values.
• ? Use a config struct when you have multiple optional parameters.
• ? Use functional options when building flexible APIs or libraries.

They each have trade-offs, but sticking with these methods keeps your code readable and consistent with the Go community's expectations.

基本上就這些。

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