proposal: error check: proposal add arrow function to let error check more simple

[simpleKV]

Proposal Details

i think we discussed arrow function previous, and discussed error check again and again
but why we are still discussing it, maybe we didn't get the sweet point
hope make a little progress

below is common code, just do somethings, f1, f2, f3( here makePeople)...
OCZ, we need check every step's err result to progress next

i add a func Dos to collect err check, it works(sample1),

but i find if Go support arrow function, we can make it more simple(sample2)

package main

import (
	"fmt"
)

type people struct {
	age  int
	name string
}

var limit int

func f1() error {
	//blabla for init something
	if limit > 1000 {
		return fmt.Errorf("reach limit")
	}
	return nil
}

func f2(age int) (int, error) {
	if age < 0 {
		return 0, fmt.Errorf("invalid age")
	}
	return age, nil
}

func makePeople(name string, age int) (*people, error) {
	if len(name) == 0 {
		return nil, fmt.Errorf("invalid name")
	}

	return &people{age, name}, nil
}

type Action func() error

func Dos(actions []Action) error {
	for i := range actions {
		err := actions[i]()
		if err != nil {
			return err
		}
	}
	return nil
}

func sample1(ageIn int) {
	var (
		err error
		age int     //middle result
		pp  *people //final result
	)

	err = Dos(
		[]Action{
			func() error {         //here is a little boring, can we make it more simple ?
				return f1()
			},
			func() error {         //can we omit the word func and error,  to deduce it ?
				age, err = f2(ageIn)
				return err
			},
			func() error {
				pp, err = makePeople("Alice", age)
				return err
			},
		})

	if err == nil {
		fmt.Println("here we got people:", *pp)
	} else {
		fmt.Println("we failed:", err)
	}
}

/*
//currently, Go does support ()=>
//
func sample2(ageIn int) {
	var (
		err error
		age int     //middle result
		pp  *people //final result
	)

	err = Dos([]Action{
		()=> f1(),               //f1 match Action
		()=> {
			age, err = f2(ageIn) //here we save age, return err only to match Action
			return err
		},
		()=> {
			pp, err = makePeople("Alice", age)  //same with above
			return err
		},
	})

	if err == nil {
		fmt.Println("here we got people:", *pp)
	} else {
		fmt.Println("we failed:", err)
	}
}
*/

func main() {
	sample1(20)

	sample1(-1)

	limit = 1005
	sample1(20)
}

[gabyhelp]

Related Issues and Documentation

• proposal: Go 2: error handling: set error as return value by default from function #39972 (closed)
• Proposal: selector-specific control flow & gofmt rules to improve error-checking readability #39372 (closed)
• proposal: Go 2: allow else err after function calls #65793 (closed)
• proposal: Go 2: Add a new operator to pass error between calls. #64493 (closed)
• proposal: Go 2: Error-Handling Paradigm with !err Grammar Sugar #63647 (closed)
• proposal: Go 2: call error handling functions with ... #64399 (closed)

_{(Emoji vote if this was helpful or unhelpful; more detailed feedback welcome in this discussion.)}

[seankhliao]

Duplicate of #21498