[slime-devel] Re: sbcl sources

[Christophe Rhodes]

Helmut Eller <e9626484 at stud3.tuwien.ac.at> writes:

> Christophe Rhodes <csr21 at cam.ac.uk> writes:
>
>>             I posted about this on slime-devel a while ago, about
>> giving a specified restart for packages that look like sb!foo -- I
>> don't remember anything coming of that, though.
>
> Have you a reference to this post?  I haven't seen it.  

My apologies.  It went to sbcl-devel, not slime-devel.
<http://www.caddr.com/macho/archives/sbcl-devel/2003-10/2644.html>
contains the message, but not the patch.

The gist of it, in this context, is to implement find-package
something like
  (defun find-package (name)
    (let ((result (%real-find-package name)))
      (unless result
        (if (= (mismatch name "SB!") 3)
            (restart-case
                (error 'bootstrap-package-not-found :name name)
              (debootstrap-package () 
                (return-from find-package 
                  (find-package (replace #\! #\- name)))))
            (error 'package-not-found :name name)))
      result))
and export BOOTSTRAP-PACKAGE-NOT-FOUND and DEBOOTSTRAP-PACKAGE (or
similar).  Then systems which want to read sbcl sources can do so by
handling BOOTSTRAP-PACKAGE-NOT-FOUND errors...

> Another, perhaps more convenient, possibility would be to associate
> special readtables with certain packages; before reading, we would
> check if the package has such a readtable and use it instead of the
> current readtable.

... modulo the readtable issues -- but even this is special-casable
for sbcl: all of sbcl's source files which need special readtable
support to be read also contain an (in-package <bootstrap-package>) as
their first non-comment form: so a handler for
BOOTSTRAP-PACKAGE-NOT-FOUND could, in addition to choosing a restart,
set the readtable for the duration of the read of that file.

  (defun read-from-file (args)
    (let ((*readtable* *readtable*))
      (handler-bind ((bootstrap-package-not-found 
                       (lambda (c) 
                         (setq *readtable* *sbcl-bootstrap-readtable*)
                         (invoke-restart 'debootstrap-package c))))
        (do-various-ready/evaly/stuff))))

or something like that.

(I should say that at present I don't use slime in sbcl development,
but I'd like to: if this gets us closer to the ability for me to type
C-c C-c in an sbcl source file and have it at least attempt to work,
count me in :-)

Cheers,

Christophe
-- 
http://www-jcsu.jesus.cam.ac.uk/~csr21/       +44 1223 510 299/+44 7729 383 757
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