EmbedObject() API and knob to change caller frames (#66)

* Fix for a bug in cbor decodeFloat
* Add EmbedObject() method
* knob to change the depth of caller frames to skip
* removed EmbedObj() for array - since it is same as Object()

binary_test.go

@@ -283,6 +283,21 @@ func ExampleEvent_Object() {
 	// Output: {"foo":"bar","user":{"name":"John","age":35,"created":"0001-01-01T00:00:00Z"},"message":"hello world"}
 }
 
+func ExampleEvent_EmbedObject() {
+	price := Price{val: 6449, prec: 2, unit: "$"}
+
+	dst := bytes.Buffer{}
+	log := New(&dst)
+
+	log.Log().
+		Str("foo", "bar").
+		EmbedObject(price).
+		Msg("hello world")
+
+	fmt.Println(decodeIfBinaryToString(dst.Bytes()))
+	// Output: {"foo":"bar","price":"$64.49","message":"hello world"}
+}
+
 func ExampleEvent_Interface() {
 	dst := bytes.Buffer{}
 	log := New(&dst)
@@ -384,6 +399,36 @@ func ExampleContext_Array_object() {
 	// Output: {"foo":"bar","users":[{"name":"John","age":35,"created":"0001-01-01T00:00:00Z"},{"name":"Bob","age":55,"created":"0001-01-01T00:00:00Z"}],"message":"hello world"}
 }
 
+type Price struct {
+	val  uint64
+	prec int
+	unit string
+}
+
+func (p Price) MarshalZerologObject(e *Event) {
+	denom := uint64(1)
+	for i := 0; i < p.prec; i++ {
+		denom *= 10
+	}
+	result := []byte(p.unit)
+	result = append(result, fmt.Sprintf("%d.%d", p.val/denom, p.val%denom)...)
+	e.Str("price", string(result))
+}
+
+func ExampleContext_EmbedObject() {
+	price := Price{val: 6449, prec: 2, unit: "$"}
+
+	dst := bytes.Buffer{}
+	log := New(&dst).With().
+		Str("foo", "bar").
+		EmbedObject(price).
+		Logger()
+
+	log.Log().Msg("hello world")
+
+	fmt.Println(decodeIfBinaryToString(dst.Bytes()))
+	// Output: {"foo":"bar","price":"$64.49","message":"hello world"}
+}
 func ExampleContext_Object() {
 	// User implements LogObjectMarshaler
 	u := User{"John", 35, time.Time{}}

context.go

@@ -59,6 +59,15 @@ func (c Context) Object(key string, obj LogObjectMarshaler) Context {
 	return c
 }
 
+// EmbedObject marshals and Embeds an object that implement the LogObjectMarshaler interface.
+func (c Context) EmbedObject(obj LogObjectMarshaler) Context {
+	e := newEvent(levelWriterAdapter{ioutil.Discard}, 0)
+	e.EmbedObject(obj)
+	c.l.context = enc.AppendObjectData(c.l.context, e.buf)
+	eventPool.Put(e)
+	return c
+}
+
 // Str adds the field key with val as a string to the logger context.
 func (c Context) Str(key, val string) Context {
 	c.l.context = enc.AppendString(enc.AppendKey(c.l.context, key), val)
@@ -321,7 +330,8 @@ func (c Context) Interface(key string, i interface{}) Context {
 type callerHook struct{}
 
 func (ch callerHook) Run(e *Event, level Level, msg string) {
-	e.caller(4)
+        //Two extra frames to skip (added by hook infra).
+	e.caller(CallerSkipFrameCount+2)
 }
 
 var ch = callerHook{}

event.go

@@ -179,6 +179,15 @@ func (e *Event) Object(key string, obj LogObjectMarshaler) *Event {
 	return e
 }
 
+// Object marshals an object that implement the LogObjectMarshaler interface.
+func (e *Event) EmbedObject(obj LogObjectMarshaler) *Event {
+	if e == nil {
+		return e
+	}
+	obj.MarshalZerologObject(e)
+	return e
+}
+
 // Str adds the field key with val as a string to the *Event context.
 func (e *Event) Str(key, val string) *Event {
 	if e == nil {
@@ -581,7 +590,7 @@ func (e *Event) Interface(key string, i interface{}) *Event {
 
 // Caller adds the file:line of the caller with the zerolog.CallerFieldName key.
 func (e *Event) Caller() *Event {
-	return e.caller(2)
+	return e.caller(CallerSkipFrameCount)
 }
 
 func (e *Event) caller(skip int) *Event {

globals.go

@@ -19,6 +19,9 @@ var (
 	// CallerFieldName is the field name used for caller field.
 	CallerFieldName = "caller"
 
+	// CallerSkipFrameCount is the number of stack frames to skip to find the caller.
+	CallerSkipFrameCount = 2
+
 	// TimeFieldFormat defines the time format of the Time field type.
 	// If set to an empty string, the time is formatted as an UNIX timestamp
 	// as integer.

journald/journald.go

@@ -1,5 +1,8 @@
 // +build !windows
 
+// Package journald provides a io.Writer to send the logs
+// to journalD component of systemd.
+
 package journald
 
 // This file provides a zerolog writer so that logs printed

log_example_test.go

@@ -4,6 +4,7 @@ package zerolog_test
 
 import (
 	"errors"
+	"fmt"
 	stdlog "log"
 	"net"
 	"os"
@@ -195,6 +196,22 @@ func (u User) MarshalZerologObject(e *zerolog.Event) {
 		Time("created", u.Created)
 }
 
+type Price struct {
+	val  uint64
+	prec int
+	unit string
+}
+
+func (p Price) MarshalZerologObject(e *zerolog.Event) {
+	denom := uint64(1)
+	for i := 0; i < p.prec; i++ {
+		denom *= 10
+	}
+	result := []byte(p.unit)
+	result = append(result, fmt.Sprintf("%d.%d", p.val/denom, p.val%denom)...)
+	e.Str("price", string(result))
+}
+
 type Users []User
 
 func (uu Users) MarshalZerologArray(a *zerolog.Array) {
@@ -248,6 +265,19 @@ func ExampleEvent_Object() {
 	// Output: {"foo":"bar","user":{"name":"John","age":35,"created":"0001-01-01T00:00:00Z"},"message":"hello world"}
 }
 
+func ExampleEvent_EmbedObject() {
+	log := zerolog.New(os.Stdout)
+
+	price := Price{val: 6449, prec: 2, unit: "$"}
+
+	log.Log().
+		Str("foo", "bar").
+		EmbedObject(price).
+		Msg("hello world")
+
+	// Output: {"foo":"bar","price":"$64.49","message":"hello world"}
+}
+
 func ExampleEvent_Interface() {
 	log := zerolog.New(os.Stdout)
 
@@ -351,6 +381,20 @@ func ExampleContext_Object() {
 	// Output: {"foo":"bar","user":{"name":"John","age":35,"created":"0001-01-01T00:00:00Z"},"message":"hello world"}
 }
 
+func ExampleContext_EmbedObject() {
+
+	price := Price{val: 6449, prec: 2, unit: "$"}
+
+	log := zerolog.New(os.Stdout).With().
+		Str("foo", "bar").
+		EmbedObject(price).
+		Logger()
+
+	log.Log().Msg("hello world")
+
+	// Output: {"foo":"bar","price":"$64.49","message":"hello world"}
+}
+
 func ExampleContext_Interface() {
 	obj := struct {
 		Name string `json:"name"`