Function aliasing

If any aliased function is to be used or provided by the thorn then the prototype must be declared with the form:

<return_type> FUNCTION <alias>(<arg1_type> <intent1> [ARRAY] <arg1>, ...)

The <return_type> must be either void, CCTK_INT, CCTK_REAL, CCTK_COMPLEX, CCTK_POINTER, or CCTK_POINTER_TO_CONST. The keyword SUBROUTINE is equivalent to void FUNCTION. The name of the aliased function <alias> must contain at least one uppercase and one lowercase letter and follow the C standard for function names. The type of each argument, <arg*_type>, must be either CCTK_INT, CCTK_REAL, CCTK_COMPLEX, CCTK_POINTER, CCTK_POINTER_TO_CONST, or STRING. All string arguments must be the last arguments in the list. The intent of each argument, <intent*>, must be either IN, OUT, or INOUT. An argument may only be modified if it is declared to have intent OUT or INOUT. If the argument is an array then the prefix ARRAY must also be given.

If the argument <arg*> is a function pointer then the argument itself (which will preceded by the return type) should be

CCTK_FPOINTER <function_arg1>(<arg1_type> <intent1> <arg1>, ...)

Function pointers may not be nested.

If an aliased function is to be required then the block

REQUIRES FUNCTION <alias>

is required.

If an aliased function is to be (optionally) used then the block

USES FUNCTION <alias>

is required.

If a function is provided then the block

PROVIDES FUNCTION <alias> WITH <provider> LANGUAGE <providing_language>

is required. As with the alias name, <provider> must contain at least one uppercase and one lowercase letter and follow the C standard for function names. Currently the only supported values of <providing_language> are C and Fortran.