[asdf-devel] bug in new ASDF

[Gary King]

Agreed. If we claim that a directory is a pathname 'without" a  
filename, then the three ways (so far) for a filename to be missing  
are for it to be `nil`, the empty string or :unspecific, Here's  
another crack at it and a sort-of test

> (defun directory-pathname-p (pathname)
>   "A directory-pathname is a pathname _without_ a filename. The three
> ways that the filename components can be missing are for it to be  
> `nil`,
> `:unspecific` or the empty string."
>   ;; a rather ugly implementation of the docstring
>   (let ((null-components (list  nil :unspecific "")))
>     (flet ((check-one (x)
> 	     (not (null (member (pathname-name pathname) null-components
> 				:test 'equal)))))
>       (and (check-one (pathname-name pathname))
> 	   (check-one (pathname-type pathname))))))

#+(or)
;;test
(every (lambda (p)
	  (directory-pathname-p p))
	(list
	 (make-pathname :name "." :type nil :directory '(:absolute "tmp"))
	 (make-pathname :name "." :type "" :directory '(:absolute "tmp"))
	 (make-pathname :name nil :type "" :directory '(:absolute "tmp"))
	 (make-pathname :name "" :directory '(:absolute "tmp"))
	 (make-pathname :type :unspecific :directory '(:absolute "tmp"))
	 (make-pathname :name :unspecific :directory '(:absolute "tmp"))
	 (make-pathname :name :unspecific :directory '(:absolute "tmp"))
	 ))


On Jul 13, 2009, at 1:57 PM, Richard M Kreuter wrote:

> Gary King writes:
>
>>> OK, I /have/ misdiagnosed this.  The logic seems actually busted in
>>> directory-pathname-p.  The problem is that, at least on allegro, you
>>> can get a valid directory pathname whose name component is neither
>>> NIL, nor :unspecific, but "" (the empty string).
>>
>> Ugh,
>>
>>> (member (pathname-name pathname) (list nil "" :unspecific) :test
>>> 'equal)
>>
>>
>> A source of the problem are pathnames that arise from things like  
>> this:
>>
>>> (make-pathname :name "" :directory '(:absolute "tmp"))
>>    #p"/tmp/"
>>> (pathname-name *)
>>     ""
>>
>> Added a call to namestring seems to be another way to canonical  
>> things
>> so I think this will also work and feels (to me) a bit more portable:
>>
>> (defun directory-pathname-p (pathname)
>>   (let ((pathname (namestring pathname)))
>>     (and (member (pathname-name pathname) (list nil :unspecific))
>> 	 (member (pathname-type pathname) (list nil :unspecific)))))
>
> I see two problems:
>
> (1) If the the host component of *DEFAULT-PATHNAME-DEFAULTS* is
>    different than the host component of PATHNAME, the parse might fail
>    or come out wrong.
>
> (2) Pathnames with "" for the name component don't have namestrings
>    under SBCL.  (IIUC, the intent there is to try to have namestring
>    parsing and unparsing be non-lossy.)
>
> I think it might do just as well to say that "" for the name counts  
> the
> same as NIL or :UNSPECIFIC for DIRECTORY-PATHNAME-P, unless somebody
> knows of implementations that don't work that way.
>
> --
> RmK

--
Gary Warren King, metabang.com
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