Existe-t-il un bon moyen de créer des types numériques adaptés à 'method.Call' en golang ?

Éditeur PHP Youzi En golang, lorsque vous utilisez la méthode method.Call pour appeler une fonction, vous pouvez rencontrer des problèmes avec les paramètres de type numérique. Cependant, il existe des moyens de résoudre ce problème. Tout d’abord, nous pouvons convertir le type numérique en type reflex.Value correspondant, puis le transmettre à la méthode method.Call. De plus, nous pouvons également utiliser la méthode de réflexion pour obtenir le type de paramètre de la fonction et effectuer le traitement correspondant en fonction du type de paramètre. En bref, grâce à ces méthodes, nous pouvons rendre le type numérique adapté à l'invocation de la méthode. Appelez la méthode en golang, résolvant ainsi ce problème.

Contenu des questions

Code Go Playground :

package main

import (
    "fmt"
    "reflect"
)

func (s StructWithManyMethods) Func1(a int, b uint, c float64) {
    fmt.Printf("func:Func1 a:%d b:%d c:%f \n", a, b, c)
}
func (s StructWithManyMethods) Func2(a string, b int, c int, d int) {
    fmt.Printf("func:Func2 a:%s b:%d c:%d d:%d\n", a, b, c, d)
}

type StructWithManyMethods struct {
}

func (s StructWithManyMethods) CallMethod(n string, p []interface{}) {
    method := reflect.ValueOf(s).MethodByName(n)
    methodType := method.Type()
    for i := 0; i < methodType.NumIn(); i++ {
        in := methodType.In(i)
        switch in.Kind() {
        case reflect.Float32:
            switch v := p[i].(type) {
            case float64:
                p[i] = float32(v)
            case float32:
                p[i] = float32(v)
            case int:
                p[i] = float32(v)
            case uint:
                p[i] = float32(v)
            case int8:
                p[i] = float32(v)
            case uint8:
                p[i] = float32(v)
            case int16:
                p[i] = float32(v)
            case uint16:
                p[i] = float32(v)
            case int32:
                p[i] = float32(v)
            case uint32:
                p[i] = float32(v)
            case int64:
                p[i] = float32(v)
            case uint64:
                p[i] = float32(v)
            }
        case reflect.Float64:
            switch v := p[i].(type) {
            case float64:
                p[i] = float64(v)
            case float32:
                p[i] = float64(v)
            case int:
                p[i] = float64(v)
            case uint:
                p[i] = float64(v)
            case int8:
                p[i] = float64(v)
            case uint8:
                p[i] = float64(v)
            case int16:
                p[i] = float64(v)
            case uint16:
                p[i] = float64(v)
            case int32:
                p[i] = float64(v)
            case uint32:
                p[i] = float64(v)
            case int64:
                p[i] = float64(v)
            case uint64:
                p[i] = float64(v)
            }
        case reflect.Int:
            switch v := p[i].(type) {
            case float64:
                p[i] = int(v)
            case float32:
                p[i] = int(v)
            case int:
                p[i] = int(v)
            case uint:
                p[i] = int(v)
            case int8:
                p[i] = int(v)
            case uint8:
                p[i] = int(v)
            case int16:
                p[i] = int(v)
            case uint16:
                p[i] = int(v)
            case int32:
                p[i] = int(v)
            case uint32:
                p[i] = int(v)
            case int64:
                p[i] = int(v)
            case uint64:
                p[i] = int(v)
            }
        case reflect.Uint:
            switch v := p[i].(type) {
            case float64:
                p[i] = uint(v)
            case float32:
                p[i] = uint(v)
            case int:
                p[i] = uint(v)
            case uint:
                p[i] = uint(v)
            case int8:
                p[i] = uint(v)
            case uint8:
                p[i] = uint(v)
            case int16:
                p[i] = uint(v)
            case uint16:
                p[i] = uint(v)
            case int32:
                p[i] = uint(v)
            case uint32:
                p[i] = uint(v)
            case int64:
                p[i] = uint(v)
            case uint64:
                p[i] = uint(v)
            }
        case reflect.Int8:
            switch v := p[i].(type) {
            case float64:
                p[i] = int8(v)
            case float32:
                p[i] = int8(v)
            case int:
                p[i] = int8(v)
            case uint:
                p[i] = int8(v)
            case int8:
                p[i] = int8(v)
            case uint8:
                p[i] = int8(v)
            case int16:
                p[i] = int8(v)
            case uint16:
                p[i] = int8(v)
            case int32:
                p[i] = int8(v)
            case uint32:
                p[i] = int8(v)
            case int64:
                p[i] = int8(v)
            case uint64:
                p[i] = int8(v)
            }
        case reflect.Uint8:
            switch v := p[i].(type) {
            case float64:
                p[i] = uint8(v)
            case float32:
                p[i] = uint8(v)
            case int:
                p[i] = uint8(v)
            case uint:
                p[i] = uint8(v)
            case int8:
                p[i] = uint8(v)
            case uint8:
                p[i] = uint8(v)
            case int16:
                p[i] = uint8(v)
            case uint16:
                p[i] = uint8(v)
            case int32:
                p[i] = uint8(v)
            case uint32:
                p[i] = uint8(v)
            case int64:
                p[i] = uint8(v)
            case uint64:
                p[i] = uint8(v)
            }
        case reflect.Int16:
            switch v := p[i].(type) {
            case float64:
                p[i] = int16(v)
            case float32:
                p[i] = int16(v)
            case int:
                p[i] = int16(v)
            case uint:
                p[i] = int16(v)
            case int8:
                p[i] = int16(v)
            case uint8:
                p[i] = int16(v)
            case int16:
                p[i] = int16(v)
            case uint16:
                p[i] = int16(v)
            case int32:
                p[i] = int16(v)
            case uint32:
                p[i] = int16(v)
            case int64:
                p[i] = int16(v)
            case uint64:
                p[i] = int16(v)
            }
        case reflect.Uint16:
            switch v := p[i].(type) {
            case float64:
                p[i] = uint16(v)
            case float32:
                p[i] = uint16(v)
            case int:
                p[i] = uint16(v)
            case uint:
                p[i] = uint16(v)
            case int8:
                p[i] = uint16(v)
            case uint8:
                p[i] = uint16(v)
            case int16:
                p[i] = uint16(v)
            case uint16:
                p[i] = uint16(v)
            case int32:
                p[i] = uint16(v)
            case uint32:
                p[i] = uint16(v)
            case int64:
                p[i] = uint16(v)
            case uint64:
                p[i] = uint16(v)
            }
        case reflect.Int32:
            switch v := p[i].(type) {
            case float64:
                p[i] = int32(v)
            case float32:
                p[i] = int32(v)
            case int:
                p[i] = int32(v)
            case uint:
                p[i] = int32(v)
            case int8:
                p[i] = int32(v)
            case uint8:
                p[i] = int32(v)
            case int16:
                p[i] = int32(v)
            case uint16:
                p[i] = int32(v)
            case int32:
                p[i] = int32(v)
            case uint32:
                p[i] = int32(v)
            case int64:
                p[i] = int32(v)
            case uint64:
                p[i] = int32(v)
            }
        case reflect.Uint32:
            switch v := p[i].(type) {
            case float64:
                p[i] = uint32(v)
            case float32:
                p[i] = uint32(v)
            case int:
                p[i] = uint32(v)
            case uint:
                p[i] = uint32(v)
            case int8:
                p[i] = uint32(v)
            case uint8:
                p[i] = uint32(v)
            case int16:
                p[i] = uint32(v)
            case uint16:
                p[i] = uint32(v)
            case int32:
                p[i] = uint32(v)
            case uint32:
                p[i] = uint32(v)
            case int64:
                p[i] = uint32(v)
            case uint64:
                p[i] = uint32(v)
            }
        case reflect.Int64:
            switch v := p[i].(type) {
            case float64:
                p[i] = int64(v)
            case float32:
                p[i] = int64(v)
            case int:
                p[i] = int64(v)
            case uint:
                p[i] = int64(v)
            case int8:
                p[i] = int64(v)
            case uint8:
                p[i] = int64(v)
            case int16:
                p[i] = int64(v)
            case uint16:
                p[i] = int64(v)
            case int32:
                p[i] = int64(v)
            case uint32:
                p[i] = int64(v)
            case int64:
                p[i] = int64(v)
            case uint64:
                p[i] = int64(v)
            }
        case reflect.Uint64:
            switch v := p[i].(type) {
            case float64:
                p[i] = uint64(v)
            case float32:
                p[i] = uint64(v)
            case int:
                p[i] = uint64(v)
            case uint:
                p[i] = uint64(v)
            case int8:
                p[i] = uint64(v)
            case uint8:
                p[i] = uint64(v)
            case int16:
                p[i] = uint64(v)
            case uint16:
                p[i] = uint64(v)
            case int32:
                p[i] = uint64(v)
            case uint32:
                p[i] = uint64(v)
            case int64:
                p[i] = uint64(v)
            case uint64:
                p[i] = uint64(v)
            }
        }
    }
    parameterValues := make([]reflect.Value, 0)
    for _, e := range p {
        parameterValues = append(parameterValues, reflect.ValueOf(e))
    }
    method.Call(parameterValues)
}

func main() {
    var s StructWithManyMethods
    s.CallMethod("Func1", []interface{}{1.0, 2.0, 3})
    s.CallMethod("Func2", []interface{}{"test", 1, 2, 3.0})
}

Sortie :

func:Func1 a:1 b:2 c:3.000000 
func:Func2 a:test b:1 c:2 d:3

Parce que j'ai besoin d'appeler la méthode de manière dynamique, mais les paramètres proviennent de différents formats de données, ce qui conduit à la nécessité de convertir le type numérique. Par exemple, lors de l'analyse de JSON dans Golang, un type de nombre non spécifié est traité comme float64, même s'il devrait probablement s'agir d'un int.

Le code a l'air horrible mais fonctionne bien.

Je me demandais s'il y avait une meilleure façon de procéder.

Solution

Utilisez l'API reflect pour convertir les valeurs.

func (s StructWithManyMethods) CallMethod(n string, p []interface{}) error {
    method := reflect.ValueOf(s).MethodByName(n)
    methodType := method.Type()
    parameterValues := make([]reflect.Value, methodType.NumIn())
    if len(p) < len(parameterValues) {
        return fmt.Errorf("expected %d parameters, got %d", len(parameterValues), len(p))
    }
    for i := range parameterValues {
        in := methodType.In(i)
        v := reflect.ValueOf(p[i])
        if !v.CanConvert(in) {
            return fmt.Errorf("cannot convert p[%d] from %s to %s", i, v.Type(), in)
        }
        parameterValues[i] = reflect.ValueOf(p[i]).Convert(in)
    }
    method.Call(parameterValues)
    return nil
}

Pour éviter la panique, ce code vérifie si la conversion est autorisée avant la conversion.

Exécutez le code sur PlayGround !

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