Logger

log.go

@@ -0,0 +1,19 @@
+package app
+
+// A Logger represents an active logging object that generates lines of output.
+type Logger interface {
+	// Log logs a message using the default formats for its operands.
+	// Spaces are always added between operands and a newline is appended.
+	Log(v ...interface{})
+
+	// Logf logs a message according to a format specifier.
+	Logf(format string, v ...interface{})
+
+	// Log logs an error using the default formats for its operands.
+	// Spaces are always added between operands and a newline is appended.
+	Error(v ...interface{})
+
+	// Logf logs an error according to a format specifier.
+	Errorf(format string, v ...interface{})
+}
+

log/log.go

@@ -0,0 +1,58 @@
+package log
+
+import "runtime"
+import "path/filepath"
+import "fmt"
+import "strings"
+
+const (
+	defaultColor string = "\033[00m"
+	accentColor  string = "\033[94m"
+	errColor     string = "\033[91m"
+)
+
+// Logger is a logger that satisfies the app.Logger interface.
+type Logger struct {
+	Debug bool
+}
+
+// Log satisfies the app.Logger interface.
+func (l *Logger) Log(v ...interface{}) {
+	if !l.Debug {
+		return
+	}
+	printPrefix("Log", accentColor)
+	fmt.Println(v...)
+}
+
+// Logf satisfies the app.Logger interface.
+func (l *Logger) Logf(format string, v ...interface{}) {
+	if !l.Debug {
+		return
+	}
+	printPrefix("Log", accentColor)
+	fmt.Printf(format, v...)
+}
+
+// Error satisfies the app.Logger interface.
+func (l *Logger) Error(v ...interface{}) {
+	printPrefix("Error", errColor)
+	fmt.Println(v...)
+}
+
+// Errorf satisfies the app.Logger interface.
+func (l *Logger) Errorf(format string, v ...interface{}) {
+	printPrefix("Error", errColor)
+	fmt.Printf(format, v...)
+}
+
+func printPrefix(level, color string) {
+	file, line := caller()
+	fmt.Printf("%s%s%s - %s: %v - ", color, strings.ToUpper(level), defaultColor, file, line)
+}
+
+func caller() (file string, line int) {
+	_, file, line, _ = runtime.Caller(3)
+	file = filepath.Base(file)
+	return
+}

log/log_test.go

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+package log
+
+import "testing"
+
+func TestLogger(t *testing.T) {
+	l := Logger{}
+
+	l.Log("hello", "world")
+	l.Logf("%s %s\n", "hello", "world")
+
+	l.Debug = true
+
+	l.Log("hello", "world")
+	l.Logf("%s %s\n", "hello", "world")
+
+	l.Error("hello", "world")
+	l.Errorf("%s %s\n", "hello", "world")
+}