Add SysReg::NewCallback for future use

include/sysreg.h

@@ -5,11 +5,12 @@
 namespace VoidFrame {
 class SysReg {
 public:
-  std::function<void(void)> *
+  const std::function<void(void)> *
   RegisterCallback(const std::string &&name,
                    std::function<void(void)> &callback);
   const std::function<void(void)> *GetCallback(std::string &&name);
   void DeleteCallback(std::string &&name);
+  const std::function<void(void)> *NewCallback(const std::string &&name);
 
 private:
   std::unordered_map<std::string, std::unique_ptr<std::function<void(void)>>>

src/sysreg.cpp

@@ -2,7 +2,7 @@
 
 using namespace VoidFrame;
 
-std::function<void(void)> *
+const std::function<void(void)> *
 SysReg::RegisterCallback(const std::string &&name,
                          std::function<void(void)> &callback) {
   callbacks[name] =
@@ -16,3 +16,11 @@ const std::function<void(void)> *SysReg::GetCallback(std::string &&name) {
 }
 
 void SysReg::DeleteCallback(std::string &&name) { callbacks.erase(name); }
+
+const std::function<void(void)> *SysReg::NewCallback(const std::string &&name) {
+  if (callbacks.count(name) == 0) {
+    callbacks[name] = std::make_unique<std::function<void(void)>>([]() {});
+  }
+
+  return callbacks[name].get();
+}