Simple flag utility
Can be used for error customizing, debug level handling
Example:
import (
"fmt"
"github.com/jloup/flag"
)
// we define our flags
var (
BadInput = flag.New("BadInput", 1)
NotAuthorized = flag.New("NotAuthorized", 2)
InternalError = flag.New("InternalError", 3)
// aggregat of flags
UserError = flag.Join("UserError", BadInput, NotAuthorized)
)
// error flagged
type MyError struct {
flag flag.Flag
Msg string
}
// MyError with flag BadInput
match := MyError{flag: BadInput, Msg: "json wanted"}
// MyError with flag InternalError
dontmatch := MyError{flag: InternalError, Msg: "server error"}
// will print
if flag.Intersect(match.flag, UserError) {
fmt.Printf("user error happened '[%s] %s'\n",
match.flag.String(), match.Msg)
}
// will not print
if flag.Intersect(dontmatch.flag, UserError) {
fmt.Printf("user error happened '[%s] %s'\n",
dontmatch.flag.String(), dontmatch.Msg)
}Output:
user error happened '[BadInput] json wanted'
Instead of flag.New, flag.InitFlag can be employed to avoid the pain to manage numerical values
import (
"fmt"
"github.com/jloup/flag"
)
// we define our flags
var (
c flag.Counter = 0
BadInput = flag.InitFlag(&c, "BadInput")
NotAuthorized = flag.InitFlag(&c, "NotAuthorized")
InternalError = flag.InitFlag(&c, "InternalError")
// aggregat of flags
UserError = flag.Join("UserError", BadInput, NotAuthorized)
)
// error flagged
type MyError struct {
flag flag.Flag
Msg string
}
// MyError with flag BadInput
match := MyError{flag: BadInput, Msg: "json wanted"}
// MyError with flag InternalError
dontmatch := MyError{flag: InternalError, Msg: "server error"}
// will print
if flag.Intersect(match.flag, UserError) {
fmt.Printf("user error happened '[%s] %s'\n",
match.flag.String(), match.Msg)
}
// will not print
if flag.Intersect(dontmatch.flag, UserError) {
fmt.Printf("user error happened '[%s] %s'\n",
dontmatch.flag.String(), dontmatch.Msg)
}Output:
user error happened '[BadInput] json wanted'
Package errors provides functions to easily aggregate, filter and pretty print errors with different type
Example:
import (
"fmt"
"github.com/jloup/errors"
"github.com/jloup/flag"
)
func main() {
var UserError = flag.New("UserError", 0)
var ParsingError = flag.New("ParsingError", 1)
var IOError = flag.New("IOError", 2)
report := errors.NewErrorAggregator()
report.New(UserError, "bad input")
report.New(UserError, "not identified")
report.New(ParsingError, "malformed")
report.New(IOError, "cannot find resource")
fmt.Printf("Report (all errors):\n%s\n",
report.Error())
fmt.Printf("Report (user errors):\n%s\n\n",
report.ErrorWithCode(UserError).Error())
fmt.Printf("Report (io and parsing errors):\n%s\n\n",
report.ErrorWithCode(flag.Join("", ParsingError, IOError)).Error())
}Output:
Report (all errors):
[UserError]
bad input
not identified
[ParsingError]
malformed
[IOError]
cannot find resource
Report (user errors):
[UserError]
bad input
not identified
Report (io and parsing errors):
[ParsingError]
malformed
[IOError]
cannot find resource