feat: sdl::Error() exception class

This is very similar to lege::lua::Error(), and simplifies throwing
errors originating from SDL code.

lib/CMakeLists.txt

@@ -11,6 +11,7 @@ add_library(lege SHARED
     modules/strict.cpp
     modules/struct.cpp
     modules/weak.cpp
+    sdl/error.cpp
     util.cpp
     )
 

lib/engine.cpp

@@ -10,9 +10,11 @@
 #include "engine.hpp"
 #include "lege.hpp"
 #include "lua/helpers.hpp"
+#include "sdl/helpers.hpp"
 #include "util.hpp"
 
 namespace lua = lege::lua;
+namespace sdl = lege::sdl;
 
 namespace lege {
 
@@ -57,8 +59,7 @@ EngineImpl::EngineImpl()
   lua_atpanic(L, lua::on_error);
   luaL_openlibs(L);
   if (SDL_InitSubSystem(m_sdl_subsystems) < 0) {
-    throw std::runtime_error(
-        fmt::format("Could not initialize SDL: {}", SDL_GetError()));
+    throw sdl::Error("Could not initialize SDL");
   }
 }
 
@@ -82,8 +83,7 @@ void EngineImpl::loadFile(const char *filename, const char *mode,
   std::size_t sz;
   auto contents = (char *)SDL_LoadFile(filename, &sz);
   if (!contents) {
-    throw std::runtime_error(fmt::format("could not load chunk \"{}\": {}",
-                                         filename, SDL_GetError()));
+    throw sdl::Error(fmt::format("could not load chunk \"{}\"", filename));
   }
   // We do this instead of manual memory management to avoid leaking memory if
   // load() throws an exception

lib/sdl/error.cpp

@@ -0,0 +1,20 @@
+#include <cstddef>
+
+#include <SDL_error.h>
+
+#include "sdl/error.hpp"
+
+namespace lege::sdl {
+
+Error::Error(std::string prefix) {
+  const char *err = SDL_GetError();
+  m_msg = prefix;
+  m_msg += ": ";
+  m_msg += err;
+}
+
+Error::~Error() {}
+
+const char *Error::what() const noexcept { return m_msg.c_str(); }
+
+} // namespace lege::sdl

lib/sdl/error.hpp

@@ -0,0 +1,22 @@
+#ifndef LIBLEGE_sdl_ERROR_HPP
+#define LIBLEGE_sdl_ERROR_HPP
+
+#include <exception>
+#include <string>
+
+namespace lege::sdl {
+
+class Error : public std::exception {
+public:
+  Error(std::string prefix = "sdl error");
+  virtual ~Error() override;
+
+  virtual const char *what() const noexcept override;
+
+private:
+  std::string m_msg;
+};
+
+} // namespace lege::sdl
+
+#endif

lib/sdl/helpers.hpp

@@ -0,0 +1,6 @@
+#ifndef LIBLEGE_SDL_HELPERS_HPP
+#define LIBLEGE_SDL_HELPERS_HPP
+
+#include "sdl/error.hpp"
+
+#endif