<HEAD> <TITLE> functionp - determine whether or not a given variable is a function
pointer </TITLE> </HEAD> <BODY BACKGROUND=http://www.imaginary.com/~beek/gifs/bg.jpg TEXT=#000000 ALINK=#FFFF00 VLINK=#550000 LINK=#000099> <center> <H1> functionp - determine whether or not a given variable is a function
pointer </H1> </center>
<p>
<b> int functionp( mixed arg ); </b>
<p>
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:
<p>
f = (: call_other, obj, func :);
<p>
The return value indicates the type of function pointer using the
values given in the driver include file "include/function.h".
<p>
<DL>
<DT> <IMG SRC = http://www.imaginary.com/Graphics/Whiteball.gif> FP_LOCAL - lfun pointer
<DT> <IMG SRC = http://www.imaginary.com/Graphics/Whiteball.gif> FP_EFUN - efun pointer
<DT> <IMG SRC = http://www.imaginary.com/Graphics/Whiteball.gif> FP_SIMUL - simul pointer
<DT> <IMG SRC = http://www.imaginary.com/Graphics/Whiteball.gif> FP_FUNCTIONAL - functional
</DL>
<p>
These values are bit values; the following flags may be added as well:
<p>
<DL>
<DT> <IMG SRC = http://www.imaginary.com/Graphics/Whiteball.gif> FP_HAS_ARGUMENTS - arguments were included in the definition
<DT> <IMG SRC = http://www.imaginary.com/Graphics/Whiteball.gif> FP_OWNER_DESTED - the owner of this function pointer has been destructed
<DT> <IMG SRC = http://www.imaginary.com/Graphics/Whiteball.gif> FP_NOT_BINDABLE - it isn't possible to rebind this function pointer
</DL>
<p>
To test if a function variable is an efun pointer:
<p>
if (functionp(f) & FP_EFUN) ...
<p>
to test if it is an efun or simul_efun:
<p>
if (functionp(f) & (FP_EFUN | FP_SIMUL)) ...
<p>
Try (very hard) to call the function:
<p>
<pre>
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);
</pre>
<p>
<HR> <ADDRESS> <A HREF=http://wagner.princeton.edu/~tim> Tim Hollebeek </A> <p> <A HREF="http://www.imaginary.com/~beek/"> Beek </A>@ZorkMUD, Lima Bean, IdeaExchange, TMI-2, and elsewhere </ADDRESS>