英文:
Pass function as argument in Go
问题
我已经尝试在Go语言中创建一个函数，用于重试任何失败的查询函数（通常是由于序列化问题）。
func retryer(functionA func(interface{}) (interface{}, []error), maxRetry int, waitBetween time.Duration) interface{} {
// 当functionA没有错误时，retryer返回functionA的返回值
// 当达到最大重试次数时，返回nil
}
我想要重试的函数看起来像这样：
func GetTopStudent(classId string) ([]Student, []error) {
// 查询classId对应班级的前10名学生
}
func GetAverageStudentScores(classId string, from time.Time, until time.Time) ([]Pair, []error) {
// 使用聚合查询所有学生的平均分，按照学生ID进行分组
// Pair类似于C++中的pair<string, string>
}
但是，结果出现了编译错误：
cannot use GetTopStudent (type func(string) ([]Student, []error)) as type func(interface{}) (interface {}, []error) in argument to retryer
我尝试稍作修改，又得到了另一个编译错误：
cannot use GetTopStudent (type func(string) ([]Student, []error)) as type func(string) (interface {}, []error) in argument to retryer
有人可以帮我创建一个通用的函数，用于包装一个函数并在出现错误时进行重试吗？
英文:
I've tried to create a function in Go that used to retry any fail query functions (usually because serialization issue).
func retryer(functionA func(interface{}) (interface{}, []error), maxRetry int, waitBetween time.Duration) interface{} {
//when no error in functionA, retryer returns whatever functionA returns
//when maxRetry is reached, returns nil
}
The functions I want to retry are looked like this
func GetTopStudent(classId string) ([]Student, []error) {
//queries top 10 students for class with classId
}
func GetAverageStudentScores(classId string, from time.Time, until time.Time) ([]Pair, []error) {
//queries all average score using aggregate, grouping by studentId
//Pair behaves like C++ pair<string,string>
}
But, the results is a compile error
cannot use GetTopStudent (type func(string) ([]Student, []error)) as type func(interface{}) (interface {}, []error) in argument to retryer
I've tried to modify it a little and I got another compile error
cannot use GetTopStudent (type func(string) ([]Student, []error)) as type func(string) (interface {}, []error) in argument to retryer
Can anyone help me creating a general function to wrap a function to retry on error?
答案1
得分: 3
更好的解决方法是使用闭包。
例如，更改retryer的类型：
func retryer(f func() error, maxRetry int, waitBetween time.Duration) error {
// 重试和等待逻辑
err := f()
// 错误处理、重试和等待逻辑
return err
}
现在调用需要重试的函数：
// ...
classId := "some value"
// ...
var st []Student
var errors []error
err := retryer(func() error {
st, errors = GetTopStudent(classId)
// 处理错误
return nil
}, numTries, waitTime)
// 在这里使用 st
请注意，以上代码是使用Go语言编写的示例代码，用于演示如何使用闭包解决问题。
英文:
A better way to solve your problem would be to use closures.
For example, change the type of retryer:
func retryer(f func() error, maxRetry int, waitBetween time.Duration) error {
// retry and wait logic
err := f()
// error handling, retry, and wait logic
return err
}
Now call functions to be retried as:
// ...
classId := "some value"
// ...
var st []Student
var errors []error
err := retryer(func() error {
st, errors = GetTopStudent(classId)
// handle errors
return nil
}, numTries, waitTime)
// use st here
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