SYNOPSIS
	mixed *map_array(mixed *arr, string fun, object ob, mixed extra)
	mixed *map_array(mixed *arr, closure cl, mixed extra)

DESCRIPTION
	Returns an array holding the items of arr mapped through
	ob->fun(element, extra) resp. the closure cl. The function fun
	in ob is called for each element in arr with that element as
	parameter. A second parameter extra is sent in each call if
	given. ob can be an object or a string. Principal function:
	
	foreach (index) arr[index] = ob->fun(arr[index],extra);
	
	The value returned by ob->fun(array[index],extra) replaces the
	existing element in the array. If arr is not an array, then 0
	will be returned.

	The extra argument is optional. ob can also be a file_name. If
	ob is omitted, this_object() is default.

EXAMPLE
	string ask_for_uid(object obj) {
	   return getuid(obj);
	}
	
	void func() {
	   string *names;
	   names = map_array(users(), "ask_for_uid", this_object());
	   /* equivalent but a bit smaller and faster is the following */
	   names = map_array(users(), #'getuid );
	   ...
	}
	
	This will create an array holding all uids of the current
	users.
	
SEE ALSO
	filter_array(E), assoc(E), intersect_alist(E), insert_alist(E),
	member_array(E), order_alist(E), sort_array(E), unique_array(E)