new idea

v2/slogger/appender.go

@@ -173,13 +173,25 @@ func (self *FilterAppender) Flush() error {
 	return self.Appender.Flush()
 }
 
-func LevelFilter(threshold Level, appender Appender) *FilterAppender {
+type LevelFilterAppender struct {
+	level Level
+	FilterAppender
+}
+
+func (self *LevelFilterAppender) AllowsLevel(level Level) bool {
+	return level >= self.level
+}
+
+func LevelFilter(threshold Level, appender Appender) Appender {
 	filterFunc := func(log *Log) bool {
 		return log.Level >= threshold
 	}
 
-	return &FilterAppender{
-		Appender: appender,
-		Filter:   filterFunc,
+	return &LevelFilterAppender{
+		threshold,
+		FilterAppender{
+			Appender: appender,
+			Filter:   filterFunc,
+		},
 	}
 }

v2/slogger/logger.go

@@ -247,6 +247,10 @@ func (self *Logger) logf(level Level, errorCode ErrorCode, messageFmt string, co
 		}
 	}
 
+	if !self.AllowsLevel(level) {
+		return nil, errors
+	}
+
 	pc, file, line, ok := nonSloggerCaller()
 	if ok == false {
 		return nil, []error{fmt.Errorf("Failed to find the calling method.")}
@@ -276,6 +280,26 @@ func (self *Logger) logf(level Level, errorCode ErrorCode, messageFmt string, co
 	return log, errors
 }
 
+type LevelTester interface {
+	AllowsLevel(Level) bool
+}
+
+func (self *Logger) AllowsLevel(level Level) bool {
+	for _, appender := range self.Appenders {
+		if levelTester, ok := appender.(LevelTester); ok {
+			if levelTester.AllowsLevel(level) {
+				return true
+			}
+		} else {
+			// only takes one unknown filter to have to make the assumption that
+			// we allow this level
+			return true
+		}
+	}
+	// if we got to here then we know none of them allow the level
+	return false
+}
+
 type Level uint8
 
 // The level is in an order such that the expressions