errutil.go

package errutil

import (
	"context"

	"github.com/samber/lo"
)

func Delay[T any](target *error) func(v T, err error) T {
	a := func(v T, err error) T {
		if *target == nil && err != nil {
			*target = err
		}
		return v
	}
	return a
}

type Person struct {
	name  string
	age   int
	email string
}

func getName(context.Context) (string, error)  { return "", nil }
func getEmail(context.Context) (string, error) { return "", nil }
func getAge(context.Context) (int, error)      { return 0, nil }

func SamplePureGo(ctx context.Context) (person *Person, err error) {
	name, err := getName(ctx)
	if err != nil {
		return
	}

	email, err := getEmail(ctx)
	if err != nil {
		return
	}

	age, err := getAge(ctx)
	if err != nil {
		return
	}

	person = &Person{
		name:  name,
		age:   age,
		email: email,
	}
	return
}

func SampleDelay(ctx context.Context) (person *Person, err error) {
	dInt := Delay[int](&err)
	dString := Delay[string](&err)
	person = &Person{
		name:  dString(getName(ctx)),
		age:   dInt(getAge(ctx)),
		email: dString(getEmail(ctx)),
	}
	return
}

func SampleLo(ctx context.Context) (person *Person, err error) {
	reason, ok := lo.TryWithErrorValue(func() error {
		person = &Person{
			name:  lo.Must(getName(ctx)),
			age:   lo.Must(getAge(ctx)),
			email: lo.Must(getEmail(ctx)),
		}
		return nil
	})
	if ok {
		return
	}

	err = reason.(error)
	return
}