Thursday, September 11, 2003 11:36 PM
Michael G Schwern <[EMAIL PROTECTED]> wrote:
> On Thu, Sep 11, 2003 at 08:36:02PM +0300, Vladimir Lipskiy wrote:
> > > Famous last words: "Our data is perfect, we don't need to check our
> > inputs."
> >
> > Yes. Our data is perfect and we don't need to check our inputs if we
> > play by rules. And the rules are:
> >
> > Always use concat_dirnames to concatenate directory names
> > Always use append_filename to append a file name to a path
> > Always keep in mind that this tool gives you a proper result
> > when you give it proper input, which is simple directory
> > names, simple file names, and paths produced by this tool only.
> > If you observe the rules, you won't get into a mess.
>
> People make mistakes. Perhaps you should produce some errors if a user
> strays outside these rules. Garbage in, garbage out: Bad. Garbage in,
> error out: Good.
It really does that. I mean that it returns a "" when it suspects its
arguments to be wrong.
> I'll admit to not knowing the general error philosophy of Parrot ops.
It could throw an internal exception, but ... I am not convinced we should
switch to that sort of indicating errors. Though what kind of errors it
ought
to provide is a subject to be arguing about.
> > >What if the volumes don't match?
> >
> > Don't match against what? concat_dirnames doesn't do matching arguments
> > against anything but PARROT_FS_DIRNAME_START and PARROT_FS_DIRNAME_END,
> > which, for example, are '[' and ']' on VMS.
>
> What if I feed you:
>
> concat_dirnames("VOL1:[dir.dir]", "VOL2:[dir.dir]")
>
> Well, I suppose that's simple, its an error since you can't usefully
> concatenate two absolute directories. Anyhow, the point is is an *error*.
Yes, and since concat_dirnames() isn't supposed to concatenate anything
but dirnames.
> > > What if I'm adding a path with a volume to one without?
> >
> > Still. You get what you do. On Mac:
> >
> > concat_dirnames('my disk:a', ':b') = ':my disk:a:b'
>
> Mac's a special case since, IIRC, :b can either mean "The volume called b"
> or "The file/directory in the current directory called b".
No. Volumes can't start with a ":". The special case is that :b can mean
either the file b or the directory b in the current directory.
So Mac treats ":my disk:a:b" as Unix treats "my disk/a/b".
> But I was unclear. I meant the other way around.
>
> concat_dirnames("b", ":my disk:a");
>
> Trying to concatenate an absolute directory onto a relative one should
> produce an error.
What do you mean by "absolute directory"?
> > File::Spec has an individual function for such purposes, catpath().
> > We can't process more than two in-arguments in PASM, so we would take
> > advantage of prepend_volume and things of such sort.
>
> Unless I'm missing something, since the volumes and root dirs are already
> attached to the filepath string, you don't need more than two arguments.
And one doesn't need to concatenate such absolute paths unless he/she/it is
a psycho. Moreover you just said yourself above that there was no use while
conacatenating absolute paths and I agreed with you. Anyway I was speaking
of
Perl5 File::Spec function catdir() which actually takes three arguments:
a volume, directory, and file.
It has to be admitted, my patch ...
/everyone rises in applause
________
(___( \_____
(___(
(___( _____
(___(__ /
| |
|_|
(~: BOO-O-O!
May I go on? Good! ... STILL needs some reworking (sniff-sniff) to effectively
resist naughty users. So I'll take a pause and lay out a new draft of the tool
in the immediate future. And if the draft pleases everybody I'll go implement
it.
