Stack tracer

tracer.go

package tracer

import (
	"fmt"
	"log"
	"runtime"
	"strings"
)

// DefaultTracer is the default tracer and has a call
// depth of 3, which works in most situations for me.
var DefaultTracer = NewTracer(3)

type Tracer struct {
	Depth int
}

// You may need to adjust the calldepth to get the proper
// resolution on the traces, depending on where the tracer
// is initialized and situated within your project. Usually
// the correct call depth can be found between 2, and 6.
func NewTracer(depth int) *Tracer {
	return &Tracer{
		Depth: depth,
	}
}

func (t *Tracer) String() string {
	pc := make([]uintptr, 10) // at least 1 entry needed
	runtime.Callers(t.Depth, pc)
	f := runtime.FuncForPC(pc[0])
	file, line := f.FileLine(pc[0])
	sfile := strings.Split(file, "/")
	sname := strings.Split(f.Name(), "/")
	return fmt.Sprintf("[%s:%d %s]", sfile[len(sfile)-1], line, sname[len(sname)-1])
}

func (t *Tracer) Panic(err error) {
	log.Panicf("%s (errType=%T, err=%q)", t, err, err)
}

func (t *Tracer) Log(err error) {
	log.Printf("%s (errType=%T, err=%q)", t, err, err)
}

func (t *Tracer) Logln(err error) {
	log.Printf("%s (errType=%T, err=%q)\n", t, err, err)
}

func (t *Tracer) Logf(format string, v ...interface{}) {
	log.Printf(t.String()+" "+format, v...)
}