the ALL object should not catch exceptions, add error handling to readme

README_new.md

@@ -123,6 +123,10 @@ from `ALL.hpp`. All classes are encapsulated in the `ALL` name space.
 Simple (and not so simple) examples are available in the `/examples` sub
 directory. The simple examples are also documented at length.
 
+Errors are treated as exceptions that are thrown of a (sub) class of
+`ALL::CustomException`. Likely candidates that may throw are `balance`,
+`setup`, `printVTKoutlines`.
+
 ### ALL object
 The ALL object can be constructed with
 
@@ -239,6 +243,12 @@ becomes
     call ALL_get_work(work) !or
     !call all%get_work(work)
 
+Since there is no exception handling in Fortran, the error handling from
+the libc is borrowed. So there are additional function that retrieve and
+reset an error number as well as an additional error message describing
+the error. These must be queried and handled by the user. An example of
+this usage is shown in the `ALL_Staggered_f` example when printing the
+VTK outlines.
 
 ### Details of the balancing methods
 #### Tensor based

include/ALL.hpp

@@ -283,12 +283,7 @@ public:
   /// method to call the setup of the chosen balancing method (not all methods
   /// require a setup)
   void setup() {
-    try {
     balancer->setup();
-    } catch (CustomException &e) {
-      std::cout << e.what() << std::endl;
-      MPI_Abort(MPI_COMM_WORLD, -1);
-    }
   }
 
   /// method the trigger the balancing step, that updates the vertices according
@@ -297,7 +292,6 @@ public:
   /// for some recursive calls of the routine by some methods
   /// @result std::vector<ALL::Point<T>> containing the shifted set of vertices
   std::vector<Point<T>> &balance() {
-    try {
     nVertices = balancer->getNVertices();
     switch (method) {
     case LB_t::TENSOR:
@@ -394,10 +388,6 @@ public:
           "Unknown type of loadbalancing passed.");
     }
     loadbalancing_step++;
-    } catch (CustomException &e) {
-      std::cout << e.what() << std::endl;
-      MPI_Abort(MPI_COMM_WORLD, -1);
-    }
     return balancer->getVertices();
   }
 
@@ -499,12 +489,7 @@ public:
   /// next-near neighbors instead of only with next neighbors
   /// @param[in] minSize the minimum size of a domain in each dimension
   void setMinDomainSize(const std::vector<T> &minSize) {
-    try {
     (balancer.get())->setMinDomainSize(minSize);
-    } catch (CustomException &e) {
-      std::cout << e.what() << std::endl;
-      MPI_Abort(MPI_COMM_WORLD, -1);
-    }
   }
 
 #ifdef ALL_VTK_OUTPUT
@@ -666,7 +651,6 @@ public:
   /// @param[in] step the number of the loadbalancing step used for numbering
   /// the output files
   void printVTKvertices(const int step) {
-    try {
     int n_ranks;
     int local_rank;
 
@@ -788,11 +772,6 @@ public:
 
       delete[] global_vertices;
     }
-
-    } catch (CustomException &e) {
-      std::cout << e.what() << std::endl;
-      MPI_Abort(MPI_COMM_WORLD, -1);
-    }
   }
 #endif