functionp()  -  determine whether or not a given variable is a function
pointer, and if so what kind


int functionp( mixed arg );


Return nonzero if 'arg' is a function pointer and zero  (0)  otherwise.
Function  pointers are variables of type 'function' as indicated in the
documentation for the type 'function', for example:

f = (: obj, func :);

The return value indicates the type of function pointer using the  val‐
ues given in the driver include file "include/function.h".

function pointer type       value
---------------------       -----
call_other                  FP_CALL_OTHER
lfun                        FP_LOCAL
efun                        FP_EFUN
simul_efun                  FP_SIMUL
functional                  FP_FUNCTIONAL

In addition, the following values will be added in some cases:
FP_HAS_ARGUMENTS            arguments provided
FP_OWNER_DESTED             creator has been dested
FP_NOT_BINDABLE             not rebindable)

The last set of values are bit values and can be tested with bit opera‐
tions. The value FP_MASK is provided for ignoring the bit values and
testing the basic type of the function pointer.


To test if a function variable is an efun pointer:

if ((functionp(f) & FP_MASK) == FP_EFUN) ...

to test if it has args:

if (functionp(f) & FP_HAS_ARGUMENTS) ...


mapp(3),  stringp(3),  pointerp(3),  objectp(3),  intp(3),  bufferp(3),
floatp(3), nullp(3), undefinedp(3), errorp(3), bind(3), lpc/types/func‐