add the ability to add an exception handler in the raise function

Author: thelfer

include/MGIS/Raise.hxx

@@ -21,6 +21,37 @@
 
 namespace mgis {
 
+  //! \brief a simple alias
+  using ExceptionHandler = void (*)(void);
+
+  /*!
+   * \brief set an exception handler
+   * \param[in] h: exception handler
+   *
+   * \code{.cpp}
+   * void handler() {
+   *   try {
+   *     throw;
+   *   } catch (std::exception& e) {
+   *     std::cerr << e.what() << '\n';
+   *   } catch (...) {
+   *     std::cerr << "unknown exception thrown";
+   *   }
+   *   std::abort();
+   * }  // end of handler
+   *
+   * mgis::setExceptionHandler(handler);
+   * mgis::raise<std::logic_error>("something went wrong");
+   * \endcode
+   */
+  MGIS_EXPORT void setExceptionHandler(ExceptionHandler);
+
+  /*!
+   * \brief return a registred exception handler, nullptr if none were
+   * registred.
+   */
+  MGIS_EXPORT ExceptionHandler getExceptionHandler();
+
   /*!
    * \brief a small wrapper used to build the exception outside the
    * `throw` statement. As most exception's classes constructors may

include/MGIS/Raise.ixx

@@ -15,18 +15,42 @@
 #ifndef LIB_MGIS_RAISE_IXX
 #define LIB_MGIS_RAISE_IXX
 
+#include <cstdlib>
+
 namespace mgis {
 
   template <typename Exception>
   void raise() {
-    Exception e;
-    throw(std::move(e));
+    const auto h = getExceptionHandler();
+    if (h != nullptr) {
+      try {
+        Exception e;
+        throw(std::move(e));
+      } catch (...) {
+        h();
+      }
+      std::abort();
+    } else {
+      Exception e;
+      throw(std::move(e));
+    }
   }  // end of raise
 
   template <typename Exception, typename... Args>
   void raise(Args&&... a) {
-    Exception e(std::forward<Args...>(a...));
-    throw(std::move(e));
+    const auto h = getExceptionHandler();
+    if (h != nullptr) {
+      try {
+        Exception e(std::forward<Args...>(a...));
+        throw(std::move(e));
+      } catch (...) {
+        h();
+      }
+      std::abort();
+    } else {
+      Exception e(std::forward<Args...>(a...));
+      throw(std::move(e));
+    }
   }  // end of raise
 
   template <typename Exception>

src/CMakeLists.txt

@@ -1,5 +1,6 @@
 mgis_library(MFrontGenericInterface SHARED
-	  ThreadPool.cxx
+  Raise.cxx
+  ThreadPool.cxx
 	  ThreadedTaskResult.cxx
 	  LibrariesManager.cxx
       Markdown.cxx