H.3 Known Bugs and Features

A few known bugs and features are listed here, some of which are hard to ``fix''. Some of them are also of little interest to users, but programmers have to be aware of the pittfalls.

• Of items with the same name only the first one can be accessed if the item is within a hierarchical set. On the top level items are accessed sequentially. In particular, a C-programming construction like

              get_set(instream,tagname)
              while(get_tag_ok(instream,myitem)) {
                  get_data(...)
              }
              get_tes(instream,tagname)
  

  would run into an infinite loop. Programmers should be careful not to construct such datasets, in particular it means one cannot portably wrap an existing dataset inside an item. Multiple history items are an example of this behavior.

• a file with multiple snapshots which vary in size doesn't get it's memory reallocated, and hence programs will likely to crash if any snapshot is larger than the first one^H.1 The ``problem'' is in the file $NEMOINC/snapshot/get_snap.c. A possible solution is to free the snapshot, or just reset the snapshot to a NULL pointer, and force it to be allocated again. One surely relies on a well designed swap space management system. Here's an example of this terrible coding kludge:

      Body *btab;
  
      for(;;) {
          get_history(instr);
          if (!get_tag_ok(instr, SnapShotTag))
              break;
          get_snap(instr, &btab, &nbody, &tsnap, &bits);
  
          ...
  
          btab = NULL;
      }   /* for(;;) */