[Openmcl-devel] with-package

[Taoufik Dachraoui]

I am wrote a very simple package system that I am using for all my
developments, I wanted to add
the macro with-package so that I can use a package temporarily and then
revert to previous context
just before using the package.

in all my developments all lisp files are packages and within each file, in
the header of the file, I use some
other packages and I export the symbols that I want them to be visible to
other packages

example:

I have the files match.lisp, syntax.lisp, utils/utils.lisp and
calculus.lisp within the directory <current-directory>

;; file match.lisp
(use utils/utils)
(export '(match))
....

;; file syntax.lisp
(use match)
(export '(syntax))
...

;; file calculus.lisp
(use syntax match utils/utils)
(export '(share))
...


This works fine and I have the possibility to use and unuse a package at
will without dealing with conflicts

to avoid some issues, that I encountered, I imposed a restriction that I
only can un-use the last used package

example:

(use package1)
...
(use package2)
...
(unuse package1) ;  this is not possible


This restriction is imposed to avoid that only a subset of some used
package is imported
(after some sequences of use and unuse), and I found the solution to this
cumbersome.


Now, is it good to have a package system that deals with conflicts
automatically
the way I am doing it? I am not sure but I found it easy to implement and
easy to use.

The only issue is with the macro with-package that I can use in situations
where I need a package
in a small section of the program I am writing

Taoufik



On Sat, Jan 12, 2013 at 4:06 PM, Robert P. Goldman <rpgoldman at sift.info>wrote:

> I would really discourage you from doing this, even if you can get it to
> work. Stuffing symbols into a package and then ripping them back out on the
> fly is pretty crude surgery. It makes the correctness of your code depend
> on arbitrary context. ("When I call this, will it cause a symbol clash
> error?").
>
> Am I correct in thinking that all you want to do is save some typing? If
> so, a macro that lets you access symbols without explicitly specifying the
> package, but doesn't have these gross side effects, is probably to be
> preferred.
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