如何在Golang中动态调用结构的所有方法？ [重复]

Question

This question already has an answer here:

• How to dump methods of structs in Golang? 1 answer

I'm building a library where once methods are added to a struct we want them to be automatically called w/o using some sort of method list.

I want to build on the work here by calling all of the methods dumped that is linked here How to dump methods of structs in Golang?.

package main

import (
    "fmt"
    "reflect"
)

type Foo struct {
    Prop string
}

func (f Foo) Bar(i int) {
    fmt.Println("Called from Foo.Bar()")
}

func (f Foo) Baz(i int) {
    fmt.Println("Called from Foo.Baz()")
}

func (f Foo) Floop(i int) {
    fmt.Println("Called from Foo.Floop()")
}

func main() {
    fooType := reflect.TypeOf(&Foo{})

    fmt.Println("--- Calling methods ---")
    for i := 0; i < fooType.NumMethod(); i++ {
        method := fooType.Method(i)

        method.Func.Call(nil)
    }
}

Also seen here: https://play.golang.org/p/gNUsANjuPV0

This will always panic w/ a message for too few arguments to .Call(). I don't see where this differs structurally from the code here: https://play.golang.org/p/HB8yB91LRme.

</div>

Answer 1

To call the method from the type, you must pass a reflect.Value instance that provides the Foo object that is the receiver plus a reflect.Value instance that provides the int argument that each function receives:

fooType := reflect.TypeOf(&Foo{})
fooVal := reflect.ValueOf(&Foo{})
fmt.Println("--- Calling methods ---")
for i := 0; i < fooType.NumMethod(); i++ {
    method := fooType.Method(i)
    arg := i + 10
    method.Func.Call([]reflect.Value{fooVal, reflect.ValueOf(arg)})
}

for instance. Note that if you call the method from the value, the receiver is provided via that value, so we get to drop the first argument:

    arg = i + 20
    reflect.Indirect(fooVal).Method(i).Call([]reflect.Value{reflect.ValueOf(arg)})

complete example on Go playground—but note that we only need to obtain the foo object once, above the loop over its methods: https://play.golang.org/p/HHk_mO2KXc6 so that the last line in the loop is just:

    fooObj.Method(i).Call([]reflect.Value{reflect.ValueOf(arg)})