replace the discarding silent logger with noop logger

logger/logger.go

@@ -1,13 +1,13 @@
 package logger
 
 import (
-	"io"
 	"log"
 	"os"
 
 	"github.com/rusq/dlog"
 )
 
+// Interface is the interface for a logger.
 type Interface interface {
 	Debug(...any)
 	Debugf(fmt string, a ...any)
@@ -16,8 +16,20 @@ type Interface interface {
 	Println(...any)
 }
 
+// Default is the default logger.  It logs to stderr and debug logging can be
+// enabled by setting the DEBUG environment variable to 1.  For example:
+//
+//	DEBUG=1 slackdump
 var Default = dlog.New(log.Default().Writer(), "", log.LstdFlags, os.Getenv("DEBUG") == "1")
 
-// note: previously ioutil.Discard which is not deprecated in favord of io.Discard
-// so this is valid only from go1.16
-var Silent = dlog.New(io.Discard, "", log.LstdFlags, false)
+// Silent is a logger that does not log anything.
+var Silent = silent{}
+
+// Silent is a logger that does not log anything.
+type silent struct{}
+
+func (s silent) Debug(...any)                {}
+func (s silent) Debugf(fmt string, a ...any) {}
+func (s silent) Print(...any)                {}
+func (s silent) Printf(fmt string, a ...any) {}
+func (s silent) Println(...any)              {}

logger/logger_test.go

@@ -0,0 +1,16 @@
+package logger
+
+import "testing"
+
+func BenchmarkSlientPrintf(b *testing.B) {
+	var l = Silent
+	for i := 0; i < b.N; i++ {
+		l.Printf("hello world, %s, %d", "foo", i)
+	}
+	// This benchmark compares the performance of the Silent logger when
+	// using io.Discard, and when using a no-op function.
+	// io.Discard: BenchmarkSlientPrintf-16    	93075956	        12.92 ns/op	       8 B/op	       0 allocs/op
+	// no-op func: BenchmarkSlientPrintf-16    	1000000000	         0.2364 ns/op	       0 B/op	       0 allocs/op
+	//
+	// Oh, look! We have an WINNER.  The no-op function wins, no surprises.
+}