Make command line flags configurable

glog.go

@@ -395,21 +395,29 @@ type flushSyncWriter interface {
 	io.Writer
 }
 
+// init sets up the defaults and runs flushDaemon.
 func init() {
-	flag.BoolVar(&logging.toStderr, "logtostderr", false, "log to standard error instead of files")
-	flag.BoolVar(&logging.alsoToStderr, "alsologtostderr", false, "log to standard error as well as files")
-	flag.Var(&logging.verbosity, "v", "log level for V logs")
-	flag.Var(&logging.stderrThreshold, "stderrthreshold", "logs at or above this threshold go to stderr")
-	flag.Var(&logging.vmodule, "vmodule", "comma-separated list of pattern=N settings for file-filtered logging")
-	flag.Var(&logging.traceLocation, "log_backtrace_at", "when logging hits line file:N, emit a stack trace")
-
-	// Default stderrThreshold is ERROR.
-	logging.stderrThreshold = errorLog
-
+	logging.stderrThreshold = errorLog // Default stderrThreshold is ERROR.
 	logging.setVState(0, nil, false)
+	logging.toStderr = true
+	logging.alsoToStderr = false
 	go logging.flushDaemon()
 }
 
+// InitFlags is for explicitly initializing the flags.
+func InitFlags(flagset *flag.FlagSet) {
+	if flagset == nil {
+		flagset = flag.CommandLine
+	}
+
+	flagset.BoolVar(&logging.toStderr, "logtostderr", logging.toStderr, "log to standard error instead of files")
+	flagset.BoolVar(&logging.alsoToStderr, "alsologtostderr", logging.alsoToStderr, "log to standard error as well as files")
+	flagset.Var(&logging.verbosity, "v", "number for the log level verbosity")
+	flagset.Var(&logging.stderrThreshold, "stderrthreshold", "logs at or above this threshold go to stderr")
+	flagset.Var(&logging.vmodule, "vmodule", "comma-separated list of pattern=N settings for file-filtered logging")
+	flagset.Var(&logging.traceLocation, "log_backtrace_at", "when logging hits line file:N, emit a stack trace")
+}
+
 // Flush flushes all pending log I/O.
 func Flush() {
 	logging.lockAndFlushAll()