package main

import "fmt"
import "os"
import "runtime"
import "path/filepath"

// Go is a basic promise implementation: it wraps calls a function in a goroutine
// and returns a channel which will later return the function's return value.
func Go(f func() error) chan error {
	ch := make(chan error)
	go func() {
		ch <- f()
	}()
	return ch
}

// if os.env DEBUG set, debug is on
func Debugf(format string, a ...interface{}) {
	if os.Getenv("DEBUG") != "" {
		_, file, line, ok := runtime.Caller(1)
		if !ok {
			file = "<unknown>"
			line = -1
		} else {
			file = filepath.Base(file)
		}
		fmt.Fprintf(os.Stderr, fmt.Sprintf("[debug] %s:%d %s\n", file, line, format), a...)
	}
}