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Error Handling

In CP2K there exist three convenient macros for error handling. They are defined in cp2k/src/common/cp_common_uses.f90, and are therefore always available. However, these macros can only be used for short messages (approximately less than 7 words), because of Fortran's line length limitation.

   CPWARN("A short warning message")
   CPABORT("A short error message")
   CPASSERT(2>1) ! For sanity checks only, not for user errors.

For longer messages one can use these two routines:

   CALL cp_warn(__LOCATION__,"A long warning message "\\&
                "which can span multiple lines and contains "\\&
                "some valuable advice for the user.")
 
   CALL cp_abort(__LOCATION__,"A long error message "\\&
                 "with even more valuable advises.")

cp_warn and CPWARN should be used sparingly, as they will produce output (and localLog files) from all MPI ranks. As such they are most useful for warning conditions that happen only on one of the ranks.

Cheat Sheet

If you want to…

print a short warning message, then you should use:
```
 CPWARN("your short message")
```

print a longer warning message, then you should use:

 CALL cp_warn(__LOCATION__,"your lengthy message, "//&
              "which can even span multiple lines")

stop the program with a short error message, then you should use:
```
 CPABORT("your short message")
```

stop the program with a longer error message, then you should use:

 CALL cp_abort(__LOCATION__,"your lengthy message, "//&
               "which can even span multiple lines")

have a simple assertion without a custom error message, then you should use:
```
 CPASSERT(your_logical_expression)
```
have a simple assertion with a short error message, then you should use:
```
 IF(.NOT.your_logical_expression) CPABORT("your short message")
```

have a complex assertion with a short error message, then you should use:

 IF(.NOT.your_super_complicated_logical_expression_that_takes_alot_of_space)&
    CPABORT("your short message")

have a lengthy assertion with a longer error message, then you should use:

 IF(.NOT.your_super_long_logical_expression_that_takes_alot_of_space)&
    CALL cp_abort(__LOCATION__,"your lengthy message"//&
                  "which again can even span multiple lines")