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26-errors.go
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/
26-errors.go
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package main
import (
"errors"
"fmt"
)
func f(arg int) (int, error){
if arg == 42 {
return -1, errors.New("can't work with 42")
}
return arg + 3, nil
}
var ErrOutOfTea = fmt.Errorf("no more tea available")
var ErrPower = fmt.Errorf("can't boil water")
func makeTea(arg int) error {
if arg == 2 {
return ErrOutOfTea
} else if arg == 4 {
return fmt.Errorf("making tea: %w",ErrPower)
}
return nil
}
func main(){
for _, i := range []int {7, 42}{
if r, e := f(i); e != nil {
fmt.Println("f failed:",e)
} else {
fmt.Println("f worked:",r)
}
}
for i := range 5 {
if err := makeTea(i); err != nil {
if errors.Is(err, ErrOutOfTea){
fmt.Println("We should buy new tea!")
} else if errors.Is(err, ErrPower){
fmt.Println("Now it is dark.")
} else {
fmt.Printf("unknown error: %s\n",err)
}
continue
}
fmt.Println("Tea is ready!")
}
}