[WIP] Exception Generator function for implementing "from_rcl_error" (r…

…os2#678)

* Created function to generate exception objects

Signed-off-by: Jacob Hassold <jhassold@dcscorp.com>

* Created function to generate exception objects

Signed-off-by: Jacob Hassold <jhassold@dcscorp.com>

* Fixed typo

Signed-off-by: Jacob Hassold <jhassold@dcscorp.com>

* Fixed typo

Signed-off-by: Jacob Hassold <jhassold@dcscorp.com>

* Throw exceptions not created by ret

Signed-off-by: Jacob Hassold <jhassold@dcscorp.com>

* Throw exceptions not created by ret

Signed-off-by: Jacob Hassold <jhassold@dcscorp.com>

* convert throw_from_rcl_error to use from_rcl_error

Mostly just a convenience function
Signed-off-by: Jacob Hassold <jhassold@dcscorp.com>

* Updated .gitignore

Please ignore
Signed-off-by: Jacob Hassold <jhassold@dcscorp.com>

* Re-ordered functions to allow compilation

Signed-off-by: Jacob Hassold <jhassold@dcscorp.com>

* Revert "Updated .gitignore"

This reverts commit bee0ee1.
Signed-off-by: Jacob Hassold <jhassold@dcscorp.com>

* restore .gitignore to original state

Signed-off-by: Shane Loretz <sloretz@osrfoundation.org>

* oops, actually restore .gitignore

Signed-off-by: Shane Loretz <sloretz@osrfoundation.org>

rclcpp/src/rclcpp/exceptions.cpp

@@ -39,8 +39,8 @@ NameValidationError::format_error(
   return msg;
 }
 
-void
-throw_from_rcl_error(
+std::exception_ptr
+from_rcl_error(
   rcl_ret_t ret,
   const std::string & prefix,
   const rcl_error_state_t * error_state,
@@ -55,24 +55,38 @@ throw_from_rcl_error(
   if (!error_state) {
     throw std::runtime_error("rcl error state is not set");
   }
-  std::string formated_prefix = prefix;
+  std::string formatted_prefix = prefix;
   if (!prefix.empty()) {
-    formated_prefix += ": ";
+    formatted_prefix += ": ";
   }
   RCLErrorBase base_exc(ret, error_state);
   if (reset_error) {
     reset_error();
   }
   switch (ret) {
     case RCL_RET_BAD_ALLOC:
-      throw RCLBadAlloc(base_exc);
+      return std::make_exception_ptr(RCLBadAlloc(base_exc));
     case RCL_RET_INVALID_ARGUMENT:
-      throw RCLInvalidArgument(base_exc, formated_prefix);
+      return std::make_exception_ptr(RCLInvalidArgument(base_exc, formatted_prefix));
     default:
-      throw RCLError(base_exc, formated_prefix);
+      return std::make_exception_ptr(RCLError(base_exc, formatted_prefix));
   }
 }
 
+void
+throw_from_rcl_error(
+  rcl_ret_t ret,
+  const std::string & prefix,
+  const rcl_error_state_t * error_state,
+  void (* reset_error)())
+{
+  // We expect this to either throw a standard error,
+  // or to generate an error pointer (which is caught
+  // in err, and immediately thrown)
+  auto err = from_rcl_error(ret, prefix, error_state, reset_error);
+  std::rethrow_exception(err);
+}
+
 RCLErrorBase::RCLErrorBase(rcl_ret_t ret, const rcl_error_state_t * error_state)
 : ret(ret), message(error_state->message), file(error_state->file), line(error_state->line_number),
   formatted_message(rcl_get_error_string().str)