有没有好的方法让数字类型适合golang中的'method.Call”？

php小编柚子在golang中，使用method.Call方法调用函数时，对于数字类型参数可能会遇到一些问题。但是，我们可以采用一些方法来解决这个问题。首先，我们可以将数字类型转换为对应的reflect.Value类型，然后再传递给method.Call方法。另外，我们还可以使用反射方法来获取函数的参数类型，并根据参数类型进行相应的处理。总之，通过这些方法，我们可以使数字类型适合golang中的method.Call方法的调用，从而解决这个问题。

问题内容

代码围棋游乐场：

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})
}

输出：

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

因为我需要动态调用方法，但是参数来自不同的数据格式，这就导致需要转换数值类型。例如，在Golang中解析JSON时，不确定的数字类型被视为float64，尽管它可能应该是int。

代码看起来很糟糕，但运行良好。

我想知道是否有更好的方法来做到这一点。

解决方法

使用reflect API 转换值。

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
}

为了防止出现恐慌，此代码在转换之前检查是否允许转换。

在 PlayGround 上运行代码！

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