with-local-package

with-local-package.lisp

(in-package :cl-user)

(defpackage :a
  (:use :cl))

(in-package :a)

(defun print-square (x)
  (print (* x x)))

(in-package :cl-user)

(defmacro with-local-package ((package) &body body)
  (let ((*package* (find-package package)))
    (let ((*print-escape* nil))
      (let ((str (princ-to-string `(progn ,@body))))
        (format *error-output* "~&Re-reading part of the code: ~a" str)
        (with-input-from-string (s str)
          (read s))))))

(defun test ()
  (with-local-package (:a)
    (print-square 3)))


; compiling (DEFUN TEST ...)
;; Re-reading part of the code: (PROGN (PRINT-SQUARE 3))
;; CL-USER> (test)

;; 9 
;; 9
;; CL-USER> (print-square 3)
; in: PRINT-SQUARE 3
;     (PRINT-SQUARE 3)
; 
; caught STYLE-WARNING:
;   undefined function: PRINT-SQUARE
; 
; compilation unit finished
;   Undefined function:
;     PRINT-SQUARE
;   caught 1 STYLE-WARNING condition
; Evaluation aborted on #<UNDEFINED-FUNCTION PRINT-SQUARE {1008FDD3F3}>.