Add a ConsoleWriter to output pretty log on the console during dev

README.md

@@ -8,16 +8,18 @@ Zerolog's API is designed to provide both a great developer experience and stunn
 
 The uber's [zap](https://godoc.org/go.uber.org/zap) library pioneered this approach. Zerolog is taking this concept to the next level with simpler to use API and even better performance.
 
-To keep the code base and the API simple, zerolog focuses on JSON logging only. As [suggested on reddit](https://www.reddit.com/r/golang/comments/6c9k7n/zerolog_is_now_faster_than_zap/), you may use tools like [humanlog](https://github.com/aybabtme/humanlog) to pretty print JSON on the console during development.
-
+To keep the code base and the API simple, zerolog focuses on JSON logging only. Pretty logging on the console is made possible using the provided `zerolog.ConsoleWriter`.
 
 ## Features
 
+* Blazing fast
+* Low to zero allocation
 * Level logging
 * Sampling
 * Contextual fields
 * `context.Context` integration
 * `net/http` helpers
+* Pretty logging for development
 
 ## Usage
 
@@ -96,6 +98,18 @@ if e := log.Debug(); e.Enabled() {
 // Output: {"level":"info","time":1494567715,"message":"routed message"}
 ```
 
+### Pretty logging
+
+```go
+if isConsole {
+    log.Logger = log.Output(zerolog.ConsoleWriter{Out: os.Stderr})
+}
+
+log.Info().Str("foo", "bar").Msg("Hello world")
+
+// Output: 1494567715 |INFO| Hello world foo=bar
+```
+
 ### Sub dictionary
 
 ```go

log.go

@@ -162,6 +162,15 @@ func Nop() Logger {
 	return New(nil).Level(Disabled)
 }
 
+// Output duplicates the current logger and sets w as its output.
+func (l Logger) Output(w io.Writer) Logger {
+	l2 := New(w)
+	l2.level = l.level
+	l2.sample = l.sample
+	copy(l2.context, l.context)
+	return l2
+}
+
 // With creates a child logger with the field added to its context.
 func (l Logger) With() Context {
 	context := l.context

log/log.go

@@ -3,6 +3,7 @@ package log
 
 import (
 	"context"
+	"io"
 	"os"
 
 	"github.com/rs/zerolog"
@@ -11,6 +12,11 @@ import (
 // Logger is the global logger.
 var Logger = zerolog.New(os.Stderr).With().Timestamp().Logger()
 
+// Output duplicates the global logger and sets w as its output.
+func Output(w io.Writer) zerolog.Logger {
+	return Logger.Output(w)
+}
+
 // With creates a child logger with the field added to its context.
 func With() zerolog.Context {
 	return Logger.With()