根据类型从泛型中进行动态函数调用

huangapple
go评论127阅读模式
英文:

Dynamic function call from generics depending on type

问题

能否使用泛型根据参数类型调用函数？
我会尽量详细解释我的任务。

例如，我有一个带有两个方法的结构体：

  1. package main
  3. import "reflect"
  5. type Cut interface {
  6.     int | int8 | int16 | int32 | int64 | float32 | float64 | string
  7. }
  9. type AudioObj struct {
  10.     fileName string
  11. }
  13. func (A AudioObj) CutIfFirstIsString(from string, to float64) {
  14.     // Cut audio file: ("00:00:03", 81.0)
  15. }
  17. func (A AudioObj) CutIfSecondIsString(from float64, to string) {
  18.     // Cut audio file: (0.3, "01:21:00")
  19. }

这是我的泛型函数：

  1. func CutAudio[S Cut, E Cut](MusicFile AudioObj, start S, end E) {
  2.     // 第一个参数是字符串。
  3.     if reflect.ValueOf(start).Kind() == reflect.String {
  4.         MusicFile.CutIfFirstIsString(start, end)
  5.     }
  7.     // 第二个参数是字符串。
  8.     if reflect.ValueOf(end).Kind() == reflect.String {
  9.         MusicFile.CutIfSecondIsString(start, end)
  10.     }
  11. }

在这里，我尝试根据函数参数类型来剪切音频文件：

  1. func main() {
  2.     audio := AudioObj{fileName: "music.mp3"}
  4.     CutAudio(audio, "00:00:03", 81.0)
  5.     CutAudio(audio, 0.3, "01:21:00")
  6. }

输出：

  1. ./prog.go:24:32: cannot use start (variable of type S constrained by Cut) as type string in argument to MusicFile.CutIfFirstIsString
  2. ./prog.go:24:39: cannot use end (variable of type E constrained by Cut) as type float64 in argument to MusicFile.CutIfFirstIsString
  3. ./prog.go:29:33: cannot use start (variable of type S constrained by Cut) as type float64 in argument to MusicFile.CutIfSecondIsString
  4. ./prog.go:29:40: cannot use end (variable of type E constrained by Cut) as type string in argument to MusicFile.CutIfSecondIsString

PlayGround: https://go.dev/play/p/1jx1-vHXDdn

是否可以将泛型类型转换为我传递给它的类型？

英文:

Is it possible to use generics to call a function depending on the type of parameters?
I will try to explain my task in as much detail as possible.

For example, I have a structure with two methods:

  1. package main
  3. import "reflect"
  5. type Cut interface {
  6.     int | int8 | int16 | int32 | int64 | float32 | float64 | string
  7. }
  9. type AudioObj struct {
  10.     fileName string
  11. }
  13. func (A AudioObj) CutIfFirstIsString(from string, to float64) {
  14.     // Cut audio file: ("00:00:03", 81.0)
  15. }
  17. func (A AudioObj) CutIfSecondIsString(from float64, to string) {
  18.     // Cut audio file: (0.3, "01:21:00")
  19. }

And this is my generic:

  1. func CutAudio[S Cut, E Cut](MusicFile AudioObj, start S, end E) {
  2.     // The first parameter is a string.
  3.     if reflect.ValueOf(start).Kind() == reflect.String {
  4.         MusicFile.CutIfFirstIsString(start, end)
  5.     }
  7.     // The second parameter is a string.
  8.     if reflect.ValueOf(end).Kind() == reflect.String {
  9.         MusicFile.CutIfSecondIsString(start, end)
  10.     }
  11. }

Here I try to cut the audio file depending on function parameters type:

  1. func main() {
  2.     audio := AudioObj{fileName: "music.mp3"}
  4.     CutAudio(audio, "00:00:03", 81.0)
  5.     CutAudio(audio, 0.3, "01:21:00")
  6. }

Output:

  1. ./prog.go:24:32: cannot use start (variable of type S constrained by Cut) as type string in argument to MusicFile.CutIfFirstIsString
  2. ./prog.go:24:39: cannot use end (variable of type E constrained by Cut) as type float64 in argument to MusicFile.CutIfFirstIsString
  3. ./prog.go:29:33: cannot use start (variable of type S constrained by Cut) as type float64 in argument to MusicFile.CutIfSecondIsString
  4. ./prog.go:29:40: cannot use end (variable of type E constrained by Cut) as type string in argument to MusicFile.CutIfSecondIsString

PlayGround: https://go.dev/play/p/1jx1-vHXDdn

It is posibile to convert generic type into the type that I sended to it?

答案1

得分: 1

你可以使用一个简单的类型开关来实现这个，但是代码会有点冗长：

  1. package main
  3. import (
  4. 	"fmt"
  5. 	"strconv"
  6. )
  8. type Cut interface {
  9. 	int | int8 | int16 | int32 | int64 | float32 | float64 | string
  10. }
  12. type AudioObj struct {
  13. 	fileName string
  14. }
  16. func (A AudioObj) CutIfFirstIsString(from string, to float64) {
  17. 	// Cut audio file: ("00:00:03", 81.0)
  18. 	fmt.Println(`Cut audio file: ("00:00:03", 81.0)`)
  19. }
  21. func (A AudioObj) CutIfSecondIsString(from float64, to string) {
  22. 	// Cut audio file: (0.3, "01:21:00")
  23. 	fmt.Println(`Cut audio file: (0.3, "01:21:00")`)
  24. }
  26. func CutAudio[S Cut, E Cut](MusicFile AudioObj, start S, end E) {
  27. 	// 第一个参数是字符串。
  28. 	if _, ok := any(start).(string); ok {
  29. 		MusicFile.CutIfFirstIsString(cutToString(start), cutToFloat(end))
  30. 	}
  32. 	// 第二个参数是字符串。
  33. 	if _, ok := any(end).(string); ok {
  34. 		MusicFile.CutIfSecondIsString(cutToFloat(start), cutToString(end))
  35. 	}
  36. }
  38. func cutToString[S Cut](cut S) string {
  39. 	var str string
  40. 	switch start := any(cut).(type) {
  41. 	case int:
  42. 		str = strconv.FormatInt(int64(start), 10)
  43. 	case int8:
  44. 		str = strconv.FormatInt(int64(start), 10)
  45. 	case int16:
  46. 		str = strconv.FormatInt(int64(start), 10)
  47. 	case int32:
  48. 		str = strconv.FormatInt(int64(start), 10)
  49. 	case int64:
  50. 		str = strconv.FormatInt(start, 10)
  51. 	case float32:
  52. 		str = strconv.FormatFloat(float64(start), 'G', -1, 32)
  53. 	case float64:
  54. 		str = strconv.FormatFloat(start, 'G', -1, 64)
  55. 	case string:
  56. 		str = start
  57. 	}
  59. 	return str
  60. }
  62. func cutToFloat[S Cut](cut S) float64 {
  63. 	var flt float64
  64. 	switch end := any(cut).(type) {
  65. 	case int:
  66. 		flt = float64(end)
  67. 	case int8:
  68. 		flt = float64(end)
  69. 	case int16:
  70. 		flt = float64(end)
  71. 	case int32:
  72. 		flt = float64(end)
  73. 	case int64:
  74. 		flt = float64(end)
  75. 	case float32:
  76. 		flt = float64(end)
  77. 	case float64:
  78. 		flt = end
  79. 	case string:
  80. 		flt, _ = strconv.ParseFloat(end, 64)
  81. 	}
  82. 	return flt
  83. }
  85. func main() {
  86. 	audio := AudioObj{fileName: "music.mp3"}
  88. 	CutAudio(audio, "00:00:03", 81.0)
  89. 	CutAudio(audio, 0.3, "01:21:00")
  90. }

Playground链接

英文:

You can do this with a good old type switch, but it is a little bit verbose:

  1. package main
  3. import (
  4. 	"fmt"
  5. 	"strconv"
  6. )
  8. type Cut interface {
  9. 	int | int8 | int16 | int32 | int64 | float32 | float64 | string
  10. }
  12. type AudioObj struct {
  13. 	fileName string
  14. }
  16. func (A AudioObj) CutIfFirstIsString(from string, to float64) {
  17. 	// Cut audio file: ("00:00:03", 81.0)
  18. 	fmt.Println(`Cut audio file: ("00:00:03", 81.0)`)
  19. }
  21. func (A AudioObj) CutIfSecondIsString(from float64, to string) {
  22. 	// Cut audio file: (0.3, "01:21:00")
  23. 	fmt.Println(`Cut audio file: (0.3, "01:21:00")`)
  24. }
  26. func CutAudio[S Cut, E Cut](MusicFile AudioObj, start S, end E) {
  27. 	// The first parameter is a string.
  28. 	if _, ok := any(start).(string); ok {
  29. 		MusicFile.CutIfFirstIsString(cutToString(start), cutToFloat(end))
  30. 	}
  32. 	// The second parameter is a string.
  33. 	if _, ok := any(end).(string); ok {
  34. 		MusicFile.CutIfSecondIsString(cutToFloat(start), cutToString(end))
  35. 	}
  36. }
  38. func cutToString[S Cut](cut S) string {
  39. 	var str string
  40. 	switch start := any(cut).(type) {
  41. 	case int:
  42. 		str = strconv.FormatInt(int64(start), 10)
  43. 	case int8:
  44. 		str = strconv.FormatInt(int64(start), 10)
  45. 	case int16:
  46. 		str = strconv.FormatInt(int64(start), 10)
  47. 	case int32:
  48. 		str = strconv.FormatInt(int64(start), 10)
  49. 	case int64:
  50. 		str = strconv.FormatInt(start, 10)
  51. 	case float32:
  52. 		str = strconv.FormatFloat(float64(start), 'G', -1, 32)
  53. 	case float64:
  54. 		str = strconv.FormatFloat(start, 'G', -1, 64)
  55. 	case string:
  56. 		str = start
  57. 	}
  59. 	return str
  60. }
  62. func cutToFloat[S Cut](cut S) float64 {
  63. 	var flt float64
  64. 	switch end := any(cut).(type) {
  65. 	case int:
  66. 		flt = float64(end)
  67. 	case int8:
  68. 		flt = float64(end)
  69. 	case int16:
  70. 		flt = float64(end)
  71. 	case int32:
  72. 		flt = float64(end)
  73. 	case int64:
  74. 		flt = float64(end)
  75. 	case float32:
  76. 		flt = float64(end)
  77. 	case float64:
  78. 		flt = end
  79. 	case string:
  80. 		flt, _ = strconv.ParseFloat(end, 64)
  81. 	}
  82. 	return flt
  83. }
  85. func main() {
  86. 	audio := AudioObj{fileName: "music.mp3"}
  88. 	CutAudio(audio, "00:00:03", 81.0)
  89. 	CutAudio(audio, 0.3, "01:21:00")
  90. }

Playground link

huangapple
  • 本文由 发表于 2022年4月15日 19:25:24
  • 转载请务必保留本文链接：https://go.coder-hub.com/71883446.html
  • generics
  • go
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