英文:
Go constructor type
问题
我想知道是否有人可以解释一下这个语法给我：
// Client may be used to make requests to the Google Maps WebService APIs
type Client struct {
httpClient *http.Client
apiKey string
baseURL string
clientID string
signature []byte
requestsPerSecond int
rateLimiter chan int
}
// ClientOption is the type of constructor options for NewClient(...).
type ClientOption func(*Client) error
var defaultRequestsPerSecond = 10
// NewClient constructs a new Client which can make requests to the Google Maps WebService APIs.
func NewClient(options ...ClientOption) (*Client, error) {
c := &Client{requestsPerSecond: defaultRequestsPerSecond}
WithHTTPClient(&http.Client{})(c)
for _, option := range options {
err := option(c)
if err != nil {
return nil, err
}
}
.....
我不明白ClientOption是什么意思。它是一个返回错误的指向Client的函数类型吗？然后在NewClient中，它看起来接受一个ClientOption类型的数组，并返回一个指向Client的新指针。我不确定这是否正确，如果有人能更详细地解释一下或给我一个类似于许多JavaScript库在构造函数中使用的选项的类比，例如：
options: {
property1: "someproperty",
property2: "anotherproperty"
}
英文:
I was wondering if someone could explain this syntax to me:
// Client may be used to make requests to the Google Maps WebService APIs
type Client struct {
httpClient *http.Client
apiKey string
baseURL string
clientID string
signature []byte
requestsPerSecond int
rateLimiter chan int
}
// ClientOption is the type of constructor options for NewClient(...).
type ClientOption func(*Client) error
var defaultRequestsPerSecond = 10
// NewClient constructs a new Client which can make requests to the Google Maps WebService APIs.
func NewClient(options ...ClientOption) (*Client, error) {
c := &Client{requestsPerSecond: defaultRequestsPerSecond}
WithHTTPClient(&http.Client{})(c)
for _, option := range options {
err := option(c)
if err != nil {
return nil, err
}
}
.....
I don't understand what's going on with ClientOption. Is it a function type on pointer to client that returns an error? And then in NewClient, it looks like it takes in an array of ClientOption types and returns a new pointer to a Client. I'm not sure if that's right and if anyone can explain that more or give me an analogy similar to what a lot of Javascript libraries do with
options: {
property1: "someproperty",
property2: "anotherproperty"
}
in a constructor.
答案1
得分: 3
ClientOption是一个接受客户端指针并返回错误（可能为nil）的函数。
例如，这是一个创建ClientOption函数的超时函数：
func WithTimeout(duration time.Duration) ClientOption {
return func(c *Client) error {
c.timeout = duration
return nil
}
}
NewClient函数接受可变数量的ClientOption参数，这些参数在'options'切片中可用。它创建一个新的Client，通过将客户端指针传递给每个ClientOption来配置它，并返回指针。
可以按以下方式使用它：
client := NewClient(WithTimeout(3 * time.Second))
请参阅Rob Pike的自引用函数和Dave Cheney的选项文章。
英文:
A ClientOption is a function accepting a client pointer and returning an error (probably nil).
For example, here's a timeout function creating a ClientOption function:
func WithTimeout(duration time.Duration) ClientOption {
return func(c *Client) error {
c.timeout = duration
return nil
}
}
The NewClient function accepts a variable number of ClientOption parameters, available in the 'options' slice. It creates a new Client, configures it by passing client pointer to each ClientOption, and returns the pointer.
It could be used as follows:
client := NewClient(WithTimeout(3 * time.Second))
See self referential functions by Rob Pike, and Dave Cheney's options article.
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