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Situation:
I'm trying to write a simple fmt.Fprintf wrapper which takes a variable number of arguments. This is the code:
func Die(format string, args ...interface{}) { str := fmt.Sprintf(format, args) fmt.Fprintf(os.Stderr, "%v\n", str) os.Exit(1) } Problem:
When I call it with Die("foo"), I get the following output (instead of "foo"):
foo%!(EXTRA []interface {}=[])
fmt.Fprintf?
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A variadic function is a function that accepts a variable number of arguments. In Golang, it is possible to pass a varying number of arguments of the same type as referenced in the function signature.
A variadic function allows you to accept any arbitrary number of arguments in a function.
Variadic parameters (Variable Length argument) are Python's solution to that problem. A Variadic Parameter accepts arbitrary arguments and collects them into a data structure without raising an error for unmatched parameters numbers.
Variadic functions receive the arguments as a slice of the type. In this case your function receives a []interface{} named args. When you pass that argument to fmt.Sprintf, you are passing it as a single argument of type []interface{}. What you really want is to pass each value in args as a separate argument (the same way you received them). To do this you must use the ... syntax.
str := fmt.Sprintf(format, args...) This is also explained in the Go specification here.
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