Golang: fmt, variadic args and %!(EXTRA type=value) error
The error was between the chair and keyboard. I mixed up the following interfaces:
func Print(v ...interface{})
func Printf(format string, v ...interface{})
Some of my code was calling the library without a format string.See here for a more detailed example: http://play.golang.org/p/Xx79qujaFp
I can't reproduce this behavior. Are you sure it's not a simple error that you forgot to show here?
https://play.golang.org/p/-jtmll17Xj
package main
import "fmt"
func Info(format string, args ...interface{}){
msg := fmt.Sprintf(format, args...)
fmt.Print(msg)
}
func main() {
Info("Hello %s", "World")
}
Prints
Hello World
According to the fmt
docs, %!(EXTRA string=WORLD)
is added to the string when you pass extra parameters, unexpected by the format. Maybe you are using the format string "Hello World"
instead of "Hello %s"
, or passing the argument twice?