fmtlog

Overview ¶

Package fmtlog adds Sprintf-style log messages as a LogLayer plugin. Register it once and every call site that passes a format string followed by arguments gets fmt.Sprintf semantics:

log.AddPlugin(fmtlog.New())

log.Info("user %d signed in", userID)
log.WithMetadata(loglayer.Metadata{"reqId": id}).
    Error("request %s failed: %v", id, err)

Without the plugin, multi-argument calls are space-joined (`fmt.Sprintf("%v", arg)` per element). Registering New opts the logger into format-string semantics: any call where the first message is a string and there are extra arguments is rewritten to fmt.Sprintf(messages[0], messages[1:]...) before downstream MessageHooks run.