callback.go

package main

import "fmt"

type callbackOpts struct {
	field string
}

type retType1 struct {
	retField string
}

type retType2 struct {
	retField string
}

type callbackFn func(callbackOpts) (interface{}, error)

func Run(cb callbackFn, cbOpts callbackOpts) error {
	// Do a bunch of stuff.
	retVal, err := cb(cbOpts)
	if err != nil {
		return err
	}
	fmt.Printf("ret val: %v\n", retVal)
	return nil
}

func callbackFn1Impl(cbOpts callbackOpts) (interface{}, error) {
	fmt.Printf("callback function 1 with options: %v\n", cbOpts)
	return &retType1{
		retField: cbOpts.field,
	}, nil
}

func callbackFn2Impl(cbOpts callbackOpts) (interface{}, error) {
	fmt.Printf("callback function 2 with options: %v\n", cbOpts)
	return &retType2{
		retField: cbOpts.field,
	}, nil
}

func main() {
	fmt.Println("Running callback #1...")
	cbOpts1 := callbackOpts{
		field: "test option 1",
	}
	if err := Run(callbackFn1Impl, cbOpts1); err != nil {
		fmt.Printf("error: %v\n", err)
		return
	}

	fmt.Println("Running callback #2...")
	cbOpts2 := callbackOpts{
		field: "test option 2",
	}
	if err := Run(callbackFn2Impl, cbOpts2); err != nil {
		fmt.Printf("error: %v\n", err)
		return
	}
	fmt.Println("success!")
}