[Openmcl-devel] with-package

[Greg Pfeil]

On 12 Jan 2013, at 7:48, Taoufik Dachraoui <dachraoui.taoufik at gmail.com> wrote:

> Now, I wanted to define with-package
> 
> (defmacro with-package ((&rest names) &body body)
>  `(progn
>     (use , at names)
>     , at body
>     (unuse ,@(reverse names))))
> 
> 
> But the problem when I use with-package as follows:
> 
> ? *package*
> #<Package "COMMON-LISP-USER">
> ?  (with-package (calculus) (share 3))
> NIL  ;;; I did not use CALCULUS::SHARE
> ? (share 3)
> 4
> ? 

This is probably secondary to the problem you are running into, but shouldn't your macro look more like:

(defmacro with-package ((&rest names) &body body)
 `(progn
    (use , at names)
    (unwind-protect (progn , at body)
      (unuse ,@(reverse names)))))

So that 1) the result of the form is the result of BODY and 2) if BODY errors, your package still gets cleaned up.