在Go语言中，当将任何接口作为参数时，可以简化类型转换。

huangapple
go评论103阅读模式
英文:

Simplify casting in Go when taking any interface as a parameter

问题

我有一个类似这样的结构体：

  1. //
  2. // HandlerInfo 用于在功能中注册网关处理程序
  3. type HandlerInfo struct {
  4. 	Fn     func(interface{})
  5. 	FnName string
  6. 	FnRm   func()
  7. }

我想传递一个函数：

  1. func StarboardReactionHandler(e *gateway.MessageReactionAddEvent) {
  2.  // foo
  3. }
  5. i := HandlerInfo{Fn: StarboardReactionHandler}

不幸的是，这会导致以下错误：

  1. 无法将 'StarboardReactionHandler'（类型为 func(e *gateway.MessageReactionAddEvent)）用作类型为 func(interface{}) 的类型

我找到了这个解决方法：

  1. func StarboardReactionHandler(e *gateway.MessageReactionAddEvent) {
  2.  // foo
  3. }
  5. func handlerCast(e interface{}) {
  6. 	StarboardReactionHandler(e.(*gateway.MessageReactionAddEvent))
  7. }
  9. i := HandlerInfo{Fn: handlerCast}

有没有办法简化需要 handlerCast 的过程，比如在 StarboardReactionHandler 或 HandlerInfo 中进行处理？也许可以使用泛型或反射？我基本上只想尽量减少这里所需的语法/样板代码。

英文:

I have a struct like so,

  1. //
  2. // HandlerInfo is used by features in order to register a gateway handler
  3. type HandlerInfo struct {
  4. 	Fn     func(interface{})
  5. 	FnName string
  6. 	FnRm   func()
  7. }

where I want to pass a func:

  1. func StarboardReactionHandler(e *gateway.MessageReactionAddEvent) {
  2.  // foo
  3. }
  5. i := HandlerInfo{Fn: StarboardReactionHandler}

Unfortunately, this results in:

  1. Cannot use 'StarboardReactionHandler' (type func(e *gateway.MessageReactionAddEvent)) as the type func(interface{})

I found this workaround:

  1. func StarboardReactionHandler(e *gateway.MessageReactionAddEvent) {
  2.  // foo
  3. }
  5. func handlerCast(e interface{}) {
  6. 	StarboardReactionHandler(e.(*gateway.MessageReactionAddEvent))
  7. }
  9. i := HandlerInfo{Fn: handlerCast}

Is there some way that I can simplify needing handlerCast, such as doing it inside my StarboardReactionHandler or in HandlerInfo? Maybe with generics or reflection? I basically just want to minimize the syntax / boilerplate that's required here.

答案1

得分: 0

你可以使用interface{}.(type)来进行类型断言。

以下是一个示例：

  1. package main
  3. import "fmt"
  5. type HandlerInfo struct {
  6. 	Fn     func(interface{})
  7. 	FnName string
  8. 	FnRm   func()
  9. }
  10. type MessageReactionAddEvent = func(a, b int) int
  12. func StarboardReactionHandler(e interface{}) {
  13. 	switch e.(type) {
  14. 	case MessageReactionAddEvent:
  15. 		fmt.Printf("%v\n", (e.(MessageReactionAddEvent))(1, 2))
  16. 	}
  18. }
  19. func add(a, b int) int {
  20. 	return a + b
  21. }
  22. func main() {
  23. 	i := HandlerInfo{Fn: StarboardReactionHandler}
  24. 	i.Fn(add)
  25. }

希望对你有帮助！

英文:

you can use interface{}.(type)

follow is a exmple:

  1. package main
  3. import "fmt"
  5. type HandlerInfo struct {
  6. 	Fn     func(interface{})
  7. 	FnName string
  8. 	FnRm   func()
  9. }
  10. type MessageReactionAddEvent = func(a, b int) int
  12. func StarboardReactionHandler(e interface{}) {
  13. 	switch e.(type) {
  14. 	case MessageReactionAddEvent:
  15. 		fmt.Printf("%v\n", (e.(MessageReactionAddEvent))(1, 2))
  16. 	}
  18. }
  19. func add(a, b int) int {
  20. 	return a + b
  21. }
  22. func main() {
  23. 	i := HandlerInfo{Fn: StarboardReactionHandler}
  24. 	i.Fn(add)
  25. }

huangapple
  • 本文由 发表于 2022年5月23日 11:17:43
  • 转载请务必保留本文链接：https://go.coder-hub.com/72342938.html
  • go
  • reflection
  • struct
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