Format.swift

import Darwin

// Uses printf() formatting
// Returns String! because vasprintf() can fail to allocate
func Format(fmt: String, args: CVarArg...) -> String! {
	var chars: UnsafePointer<CChar> = nil
	let n = withUnsafePointer(&chars) {
		charp in
		withVaList(args) {
			va_list in
			fmt.withCString { vasprintf(charp, $0, va_list) }
		}
	}
	if n < 0 {
		// vasprintf failed to allocate
		return nil
	}
	let s = String.fromCString(chars)
	free(chars)
	return s
}

println(Format("test: %04d", 3 as Int32))