Start with pattern_layout configuration...

src/loggers/pattern_layout.cxx

@@ -17,18 +17,31 @@ using namespace logging;
 struct pattern_layout : public layout {
   static std::shared_ptr<layout> create(properties const &);
   
-  pattern_layout(std::string const & fmt);
+  pattern_layout(properties const & props);
   std::string format(logpacket const & pkt) const override;
   
   class format formatter;
 };
 
+using namespace logging::property;
+properties const DEFAULT_PATTERN_LAYOUT{_obj({
+  {"charset", _v("en_US.UTF-8")},
+  {"pattern", {}},
+  {"patternSelector", {}},
+  {"replace", _v("")},
+  {"header", _v("")},
+  {"footer", _v("")},
+  {"disableAnsi", _v(false)},
+  {"noConsoleNoAnsi", _v(false)}
+})};
+
 std::shared_ptr<layout> pattern_layout::create(properties const & props) {
-  return std::make_shared<pattern_layout>(props["pattern"]);
+  properties const actual = DEFAULT_PATTERN_LAYOUT.mergedWith(props);
+  return std::make_shared<pattern_layout>(actual);
 }
 
-pattern_layout::pattern_layout(std::string const & fmt) :
-  formatter(format::parse_format_string(fmt)) {}
+pattern_layout::pattern_layout(properties const & props) :
+  formatter(format::parse_format_string(props["pattern"])) {}
 
 std::string pattern_layout::format(logpacket const & pkt) const {
   return formatter.process(pkt);