converter 包

converter 包提供了一个 Converter 实现，帮助用户快速构建名为 converter 的 Operator：

  1. // OperatorKind means opeartor kind. All operators generated in this package
  2. // are has kind `converter`.
  3. const OperatorKind = "converter"
  5. // Converter describes a converter.
  6. type Converter interface {
  7.     definition.Operator
  8. }
  10. // For creates converter for a converter func.
  11. //
  12. // A converter func should has signature:
  13. //  func f(context.Context, string, AnyType) (AnyType, error)
  14. // The second parameter is a string that is used to generate error.
  15. // AnyType can be any type in go. But struct type and
  16. // built-in data type is recommended.
  17. func For(f interface{}) Converter {
  18.     return definition.OperatorFunc(OperatorKind, f)
  19. }

这个包非常简单，只是提供了一个方法帮助用户将转换函数生成为 Operator。