包选择器与字符串名称

huangapple
go评论114阅读模式
英文:

Package selector with string name

问题

我正在尝试找出一种方法来从多个包中访问具有名称的结构体。

这是我的结构体：

  1. collector/package1
  2. collector/package2

..
package1 包含：

  1. package collector
  3. type NewRule struct {
  4. }

..
package2 包含：

  1. package collector
  3. type OldRule struct {
  4. }

....

在我的 main.go 文件中：

  1.  import "github.com/mypackage/collector"
  3.  sliceOfCollector := []string{"NewRule", "OldRule"}
  5.  for _, col := range sliceOfCollector{
  6.       // 如何使用上述 collector 名称 `col` 创建结构体实例。
  7.  }
英文:

I am trying to figure out a way to access struct from multiple packages with name.

Here is my structure:

  1. collector/package1
  2. collector/package2

..
package1 contains:

  1. package collector
  3. type NewRule struct {
  4. }

..
package2 contains:

  1. package collector
  3. type OldRule struct {
  4. }

....

In my main.go:

  1.  import "github.com/mypackage/collector"
  3.  sliceOfCollector := []string{"NewRule", "OldRule"}
  5.  for _, col := range sliceOfCollector{
  6.       // How to use the above collector name `col` to create struct instance.
  7.  }

答案1

得分: 3

使用reflect.New和struct类型。在Go语言中，你必须使用类型来动态创建一个新的实例，而不是字符串。

示例：要动态创建结构体实例，可以这样做：

  1. package main
  3. import "reflect"
  5. import (
  6.    "github.com/collector/package1"
  7.    "github.com/collector/package2"
  8. )
  10. func main() {
  11.     sliceOfCollector := make([]reflect.Type, 0)
  12.     sliceOfCollector = append(sliceOfCollector, reflect.TypeOf((*package1.NewRule)(nil)).Elem())
  13.     sliceOfCollector = append(sliceOfCollector, reflect.TypeOf((*package2.OldRule)(nil)).Elem())
  15.     for _, collectorType := range sliceOfCollector {
  16.         col := reflect.New(collectorType)
  17.         fmt.Printf("%#v\n", col)
  18.     }
  19. }

之后，你可以使用type assertions，如col.Interface().(*package1.NewRule)。

编辑：

在评论互动之后，添加了以下内容。

使用工厂方法创建实例，这只是一个想法。

  1. func main() {
  2.     sliceOfCollector := []string{"NewRule", "OldRule"}
  3.     
  4.     for _, col := range sliceOfCollector {
  5.         rule := CreateRuleByName(col)
  6.         fmt.Printf("%#v\n", rule)
  7.     }
  8. }
  10. func CreateRuleByName(name string) interface{} {
  11.     switch name {
  12.     case "NewRule":
  13.        return &package1.NewRule{}
  14.     case "OldRule":
  15.        return &package2.OldRule{}
  16.     default:
  17.        return nil
  18.     }
  19. }
英文:

Use reflect.New with struct type. In Go you have to use type to create a new instance dynamically not string.

Example: To create struct instance dynamically, you can do

  1. package main
  3. import "reflect"
  5. import (
  6.    "github.com/collector/package1"
  7.    "github.com/collector/package2"
  8. )
  10. func main() {
  11. 	sliceOfCollector := make([]reflect.Type, 0)
  12. 	sliceOfCollector = append(sliceOfCollector, reflect.TypeOf((*package1.NewRule)(nil)).Elem()})
  13. 	sliceOfCollector = append(sliceOfCollector, reflect.TypeOf((*package2.OldRule)(nil)).Elem()})
  15. 	for _, collectorType := range slice sliceOfCollector {
  16. 		col := reflect.New(collectorType)
  17. 		fmt.Printf("%#v\n", col)
  18. 	}
  19. }

You can use type assertions after that col.Interface().(*package1.NewRule)

EDIT:

After comment interaction, added following.

Creating a instance using factory method. Just an idea.

  1. func main() {
  2.     sliceOfCollector := []string{"NewRule", "OldRule"}
  3.     
  4.     for _, col := range sliceOfCollector {
  5.         rule := CreateRuleByName(col)
  6.         fmt.Printf("%#v\n", rule)
  7.     }
  8. }
  10. func CreateRuleByName(name string) interface{} {
  11.     switch name {
  12.     case "NewRule":
  13.        return &package1.NewRule{}
  14.     case "OldRule":
  15.        return &package2.OldRule{}
  16.     default:
  17.        return nil
  18.     }
  19. }

huangapple
  • 本文由 发表于 2017年7月13日 06:42:41
  • 转载请务必保留本文链接：https://go.coder-hub.com/45068666.html
  • go
  • struct
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