anchor.diff:    (let ((str (gensym)))
       `(let ((,str ,lisp-string))
          (if (null ,str)
  -           (let ((,foreign-string (cffi:null-ptr)))
  +           (let ((,foreign-string (cffi:null-pointer)))
                ,@body)
              (cffi:with-foreign-string (,foreign-string ,str)
                ,@body)))))
  
positive.code:   (let ((str (gensym)))
      `(let ((,str ,obj))
         (if (null ,str)
             (cffi:null-ptr)
             (cffi:foreign-string-alloc ,str)))))
  
  (defmacro allocate-foreign-string (size &key unsigned)
  
negative.code: 
  (defmacro null-pointer-p (ptr)
    "Return true if PTR is a null pointer."
    `(cffi:null-pointer-p ,ptr))
  
  (defparameter +null-cstring-pointer+ (cffi:null-pointer)
    "A constant NULL string pointer.")
  
  (defmacro char-array-to-pointer (obj)
  