Macro: WITH-UNIQUE-NAMES

Documentation

Evaluate BODY with BINDINGS bound to fresh unique symbols. Syntax: WITH-UNIQUE-NAMES ( [ var | (var x) ]* ) declaration* form* Executes a series of forms with each VAR bound to a fresh, uninterned symbol. The uninterned symbol is as if returned by a call to GENSYM with the string denoted by X - or, if X is not supplied, the string denoted by VAR - as argument. The variable bindings created are lexical unless special declarations are specified. The scopes of the name bindings and declarations do not include the Xs. The forms are evaluated in order, and the values of all but the last are discarded (that is, the body is an implicit PROGN).

Source

(defmacro with-unique-names ((&rest bindings) &body body)
  "Evaluate BODY with BINDINGS bound to fresh unique symbols.

Syntax: WITH-UNIQUE-NAMES ( [ var | (var x) ]* ) declaration* form*

Executes a series of forms with each VAR bound to a fresh,
uninterned symbol. The uninterned symbol is as if returned by a call
to GENSYM with the string denoted by X - or, if X is not supplied, the
string denoted by VAR - as argument.

The variable bindings created are lexical unless special declarations
are specified. The scopes of the name bindings and declarations do not
include the Xs.

The forms are evaluated in order, and the values of all but the last
are discarded \(that is, the body is an implicit PROGN)."
  ;; reference implementation posted to comp.lang.lisp as
  ;; <cy3bshuf30f.fsf@ljosa.com> by Vebjorn Ljosa - see also
  ;; <http://www.cliki.net/Common%20Lisp%20Utilities>
  `(let ,(mapcar (lambda (binding)
                   (check-type binding (or cons symbol))
                   (destructuring-bind (var &optional (prefix (symbol-name var)))
                       (if (consp binding) binding (list binding))
                     (check-type var symbol)
                     `(,var (gensym ,(concatenate 'string prefix "-")))))
                 bindings)
     ,@body))