functionp |
Discworld driver help |
functionp |
Name
functionp() - determine whether or not a given variable is a function pointer
Synopsis
int functionp( mixed arg );
Description
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 = (: call_other, obj, func :);
The return value indicates the type of function pointer using the values given in the driver include file <function.h>.
| FP_LOCAL | lfun pointer | |
| FP_EFUN | efun pointer | |
| FP_SIMUL | simul pointer | |
| FP_FUNCTIONAL | functional |
These values are bit values; the following flags may be added as well:
| FP_HAS_ARGUMENTS | arguments were included in the definition | |
| FP_OWNER_DESTED | the owner of this function pointer has been destructed | |
| FP_NOT_BINDABLE | it isn't possible to rebind this function pointer |
To test if a function variable is an efun pointer:
if (functionp(f) & FP_EFUN) ...
to test if it is an efun or simul_efun:
if (functionp(f) & (FP_EFUN | FP_SIMUL)) ...
Try (very hard) to call the function:
if (functionp(f) & FP_OWNER_DESTED) {
if (functionp(f) & FP_NOT_BINDABLE)
error("Function could not be rebound.\n");
f = bind(f, this_object());
}
evaluate(f);
