How Golang defines error

How Golang defines error

During the development process, when the error content returned by the standard library could no longer meet our needs, we found builtin. error in go is an interface,

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type error interface { Error() string }

So you only need to create a structure containing the Error() string function.

1. Create a new errors package under go path

vim $GOPATH/github.com/mypractise/error/errors.go

package errors type Error struct { ErrCode int ErrMsg string } func NewError(code int, msg string) *Error { return &Error{ErrCode: code, ErrMsg: msg} } func (err *Error) Error() string { return err.ErrMsg }

2. Start calling the errors package

vim ./test.go

package main import ( "encoding/json" "errors" "fmt" myerr "github.com/mypractise/errors" ) func myErr() error { err := myerr.NewError(2, "err test") return err } func staErr() error { m := make(map[string]string) err := json.Unmarshal([]byte(""), m) if err != nil { return err } return errors.New("aaaaa") } func main() { err1 := staErr() fmt.Println("------sta err:", err1.Error()) err2 := myErr() fmt.Println("------my err:", err2.Error(), err2.(*myerr.Error).ErrCode) }

3. Run the test

go run ./test.go

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