+class AlutError
+: public std::runtime_error {
+
+public:
+ explicit AlutError(ALenum);
+ AlutError(ALenum, const std::string &);
+
+};
+
+class SDLError
+: public std::runtime_error {
+
+public:
+ SDLError();
+ explicit SDLError(const std::string &);
+
+};
+
+class NetError
+: public std::runtime_error {
+
+public:
+ NetError();
+ explicit NetError(const std::string &);
+
+};