聊聊golang的error增强

package main

import (
    "errors"
    "fmt"
    "os"
)

var DemoErr = errors.New("test error stack")

// https://itnext.io/golang-error-handling-best-practice-a36f47b0b94c
func main() {
    if err := methodA(false); err != nil {
        fmt.Printf("%+v\n", err)
    }

    if err := methodA(true); err != nil {
        fmt.Printf("%+v\n", err)
        fmt.Printf("%+v\n", errors.Unwrap(err))
        fmt.Printf("%+v\n", errors.Unwrap(errors.Unwrap(err)))

        fmt.Println("errors.Is(err, DemoErr)=", errors.Is(err, DemoErr))
        fmt.Println("errors.As(err, &DemoErr)=", errors.As(err, &DemoErr))

        var pe *os.PathError
        fmt.Println("errors.Is(err, pe)=", errors.Is(err, pe))
        fmt.Println("errors.As(err, &pe)=", errors.As(err, &pe))
    }
}

func methodA(wrap bool) error {
    if err := methodB(wrap); err != nil {
        if wrap {
            return fmt.Errorf("methodA call methodB error: %w", err)
        }
        return err
    }
    return nil
}

func methodB(wrap bool) error {
    if err := methodC(); err != nil {
        if wrap {
            return fmt.Errorf("methodB call methodC error: %w", err)
        }
        return err
    }
    return nil
}

func methodC() error {
    return DemoErr
}

test error stack
methodA call methodB error: methodB call methodC error: test error stack
methodB call methodC error: test error stack
test error stack
errors.Is(err, DemoErr)= true
errors.As(err, &DemoErr)= true
errors.Is(err, pe)= false
errors.As(err, &pe)= false