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OPEN for :OUTPUT with version :NEWEST
- To: RAM%CMU-CS-C@SU-DSN
- Subject: OPEN for :OUTPUT with version :NEWEST
- From: Daniel L. Weinreb <DLW%SCRC-TENEX%MIT-MC@SU-DSN>
- Date: Wed, 22 Jun 1983 15:27:00 -0000
- Cc: common-lisp@SU-AI
- In-reply-to: The message of 22 Jun 83 07:28-EDT from Rob MacLachlan <RAM at CMU-CS-C>
Date: Wed, 22 Jun 1983 07:28 EDT
From: Rob MacLachlan <RAM@CMU-CS-C>
In the DEC VAX implementation I have been using,
the implementer evidently decided that if an explicit version is
specified then an attempt to open for write will error, not supersede,
regardless of the :if-exists option. Perhaps this is wrong, but the
manual is not very clear on this point.
It's definitely wrong, and I think it's clear from the manual that it's
wrong, although the manual isn't completely clear about a lot of details
of this stuff.
It seems to me that the entire point of Pathnames is that they (may)
permit implementation independant file handling code to be written.
Implementers should be given plenty of rope, but it should be possible
to say something as simple as "I want to write this file" in a
portable fashion, or the whole exercise is pointless.
Certainly. That's why I sent in my previous message. There has to
be a defined way for all this stuff to work, or else it's useless for
writing portable programs and should be removed from the manual. I
think the former is the way to go.
Another point about versions; not all operating systems have any
real concept of versions. It would seem dubious to forbid an
implementation of Common Lisp on UNIX.
That's right; the manual ought to address this point. Actually, I think
what will happen is that now that the Bible of Common Lisp is nearly
finished, it is time to start writing the Talmud, you should pardon the
analogy. That is, the Commentary and Interpretation by the Learned
Rabbis of Common Lisp. The commentary on this chapter would say
that in Rabbi Weinreb's opinion, the meaning of the scriptures is
that on operating systems without version numbers, you simply ignore
the version component of pathnames when doing an OPEN, and acts as
if every pathname had an explicit numeric version of, say, 1, and all
files in the file system are of version 1. This is what the Lisp
Machine pathname system does, essentially.