A New My String Fyne Binding Thing

MyStringThing.go

package main

import (
	"fyne.io/fyne/v2/data/binding"
	"log"
)

type MySprintfString struct {
	binding.String

	Original binding.String
	inFunc   func(string) string
	outFunc  func(string) string
	format   string
	source   binding.DataItem
	err      error
}

func NewMyString(str string, inF func(string) string, outF func(string) string) *MySprintfString {
	it := binding.NewString()
	err := it.Set(str)
	if err != nil {
		log.Fatalf("Error: %w\n", err)
	}

	ret := &MySprintfString{
		Original: it,
		String:   it,
		source:   it,
		inFunc:   inF,
		outFunc:  outF,
	}

	ret.source.AddListener(ret)

	return ret
}

func NewMyStringOnlyIn(str string, f func(string) string) *MySprintfString {
	return NewMyString(str, f, func(s string) string { return s })
}

func NewMyStringOnlyOut(str string, f func(string) string) *MySprintfString {
	return NewMyString(str, func(s string) string { return s }, f)
}

func (s *MySprintfString) DataChanged() {
	log.Printf("Data changed: (%v) %#v\n", s.Original, s)
	val, err := s.Get()
	if err != nil {
		log.Fatalf("Error: %w\n", err)
	}

	err = s.Set(s.inFunc(val))
	if err != nil {
		log.Fatalf("Error: %w\n", err)
	}
}

func (s *MySprintfString) Get() (string, error) {
	value := s.source

	it := value.(binding.String)

	val, err := it.Get()
	if err != nil {
		log.Fatalf("Error: %w", err)
	}

	return s.outFunc(val), nil
}

func (s *MySprintfString) Set(str string) error {
	value := s.source
	val := value.(binding.String)

	err := val.Set(str)
	if err != nil {
		return err
	}

	return nil
}

func StringMyString(str string, f func(string) string) *MySprintfString {
	return NewMyStringOnlyIn(str, f)
  
}