不能使用函数（func（）类型）作为参数中的类型

  • Z时代
  • 2024-01-10
  • 分类：问答

package main
import (
    "log"
    "strings"
    "asl.com/asl"
)
/*
Trivial service to demonstrate chaining service together
Message starts in originator, travels through a couple formatters, and then gets back to originator
*/
type MessageTest struct {
    Body string `json:"body"`
}
var s *asl.Service
func main() {
    var (
        err error
        cid string
    )
    //var m MessageDelivery
       var g asl.MessageHandler
       g = UpperCaseHandler
    //  UpperCaser := asl.NewService("UpperCaser", "", false)
    UpperCaser := asl.NewService("UpperCaser")
    if err = UpperCaser.ConsumeFunc("asl-service-uc", []string{"asl-service-uc"},func() interface{} {
        return ""
    },g); err != nil {
        log.Fatalf("Error starting consumer: %v", err)
    }
    //  Repeater := asl.NewService("Repeater", "", false)
    Repeater := asl.NewService("Repeater")
    if err = Repeater.ConsumeFunc("asl-service-repeat", []string{"asl-service-repeat"}, func() interface{} {
        return ""
    }, RepeatHandler); err != nil {
        //if err = Repeater.ConsumeFunc("asl-service-repeat", []string{"asl-service-repeat"}, mg asl.MessageGenerator, mh asl.MessageHandler); err != nil {
        log.Fatalf("Error starting consumer: %v", err)
    }
    //  originator := asl.NewService("Originator", "", false)
    originator := asl.NewService("Originator")
    deliveryChan := make(chan asl.MessageDelivery)
    m := asl.MessagePublishing{
        Message:     MessageTest{"this is a test"},
        RoutingKeys: []string{"asl-service-uc", "asl-service-repeat"},
    }
    if cid, err = originator.RPCPublish(m, deliveryChan); err != nil {
        log.Fatalf("Failed to publish: %v", err)
    }
    message := <-deliveryChan
    log.Printf("Originator Got: %+v", message.Message)
    originator.RemoveQueue(cid)
    UpperCaser.Wait()
}
func UpperCaseHandler(md asl.MessageDelivery) {
     s.Reply(MessageTest{strings.ToUpper(md.Message.(string))}, md.Delivery)
}
func RepeatHandler(md asl.MessageDelivery) {
     s.Reply(MessageTest{strings.Repeat(md.Message.(string), 5)}, md.Delivery)
}
package asl

Error

./chains.go:26:10：不能在作业中使用UpperCaseHandler（typefunc（asl.MessageDelivery））作为asl.MessageHandler类型./chains.go:37:86：无法使用RepeatHandler（类型func（asl.MessageDelivery））与Repeater.ConsumeFunc的参数中的asl.MessageHandler类型相同

type MessageDelivery struct {
    Delivery amqp.Delivery
    Message  interface{}
    Error    error
    Context  *Context
}    
type MessageGenerator func() interface{}
type MessageHandler func(MessageDelivery) (interface{}, error)

我试图运行代码，哪里出了问题，我该如何正确地将函数作为参数传递给另一个函数。该函数返回接口和错误。虽然函数以MessageDelivery

Struct作为参数，但是函数签名是相同的。

回答：

您正确地将该函数作为参数传递，但是它们与预期的签名不匹配。将功能更改为：

func UpperCaseHandler(md busboy.MessageDelivery) (interface{}, error} {
     s.Reply(MessageTest{strings.ToUpper(md.Message.(string))}, md.Delivery)
     return nil, nil
}
func RepeatHandler(md busboy.MessageDelivery) (interface{}, error} {
     s.Reply(MessageTest{strings.Repeat(md.Message.(string), 5)}, md.Delivery)
     return nil, nil
}

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