Hello,
This a question about the use of the :defaults argument in make-pathname
when the :directory argument is a relative directory.
(make-pathname
:defaults (make-pathname :directory '(:absolute "a-better-acl"))
:directory '(:relative "five"))
With ACL4W :
#P"\\a-better-acl\\five\\"
With ACL5 beta, the
#p"five\\"
Here are some relevant excerpts from the CL-hyper-spec:
----
Function MAKE-PATHNAME
Syntax:
make-pathname &key host device directory name type version defaults case
=> pathname
...
After the components supplied explicitly by host, device, directory,
name, type, and version are filled in, the merging rules used by
merge-pathnames are used to fill in any unsupplied components from the
defaults supplied by defaults.
...
Function MERGE-PATHNAMES
Syntax:
merge-pathnames pathname &optional default-pathname default-version
=> merged-pathname
...
If pathname does not specify a host, device, directory, name, or type,
each such component is copied from default-pathname. If pathname does
not specify a name, then the version, if not provided, will come from
default-pathname, just like the other components.
...
Pathname merging treats a relative directory specially. If
(pathname-directory pathname) is a list whose car is :relative, and
(pathname-directory default-pathname) is a list, then the merged
directory is the value of
(append (pathname-directory default-pathname)
(cdr ;remove :relative from the front
(pathname-directory pathname)))
----
I suppose that the implementors of ACL4W have applied the special treat of
a relative directory, as stated in the merge-pathnames specification (which
I consider the right choice - intuitively). The implementors of ACL will
say that `unsupplied' is the key word in the make-pathname specification
(thus in my example, because there is a :directory argument, the directory
component of the :defaults argument has to be ignored).
Thanks in advance for any comments.
Francis
--
Francis Leboutte
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From: Erik Naggum
Subject: Re: Which make-pathname function is broken?
Date:
Message-ID: <3108454610901449@naggum.no>
* Francis Leboutte
| This a question about the use of the :defaults argument in make-pathname
| when the :directory argument is a relative directory.
we've been around this one before, and the emerging consensus was that
MAKE-PATHNAME creates a new pathname object from the supplied parameters
directly as specified, and that only the unsupplied arguments are taken
from the DEFAULTS argument. therefore, if you supply a DIRECTORY
argument to MAKE-PATHNAME, it is immaterial what the DIRECTORY component
of the DEFAULTS argument is.
initially, I had the same intuitive understanding as you do, but then I
received an intuition upgrade, a.k.a. experience of enlightenment. :)
conclusion: ACL 5.0.beta is correct, and ACL4W is broken.
#:Erik
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