Hi Julian
On Mon, Sep 24, 2007 at 10:34:59AM +0000, Julian Mehnle wrote:
> Ola Lundqvist wrote:
> > > `perldoc -f do` says:
> > > | If "do" cannot read the file, it returns undef and sets $! to the
> > > | error. If "do" can read the file but cannot compile it, it returns
> > > | undef and sets an error message in [EMAIL PROTECTED] If the file is
> > > | successfully compiled, "do" returns the value of the last
> > > | expression evaluated.
> > >
> > > Thus relying on $! and $@ is officially sanctioned.
> >
> > I can not see that. It do not say anything about the $! or $@ when the
> > expression return true. It only tell that they are set when it returns
> > false.
> >
> > The above statements formalized:
> > If X return undef and set $!
> > if Y return undef and set $@
> > if Z return $lastexpr
> >
> > I can not see anything about
> > if return true, set $! = 0, set $@ = 0;
> >
> > It may be so that it do that and I did some test code that verifies
> > that. However I do not want to rely on undocumented features too much
> > if there are documented features that I can rely on.
>
> You're right, and it even actually says (in `perldoc perlvar`) that $!
> does NOT get set to 0 if there is no failure. Perhaps you could
> explicitly set $! to 0 before the do() call, though?
Ok, good to know.
> About $@, I'm certain that it gets set to "" if the file could be read and
> compiled successfully.
Ok that is likely so.
> > > I think the "check whether do() returns true" idiom is a remnant from
> > > old times when Perl didn't know exceptions ($@).
> >
> > This is the result of the test code:
> >
> > Condition return $! $@
> > --------------------------------------
> > Read error undef string ""
> > Syntax error undef "" string
> > No statements undef "" ""
> > last 0 0 "" ""
> > last 1 1 "" ""
> >
> > The "" above could also be undef, but I did not have the time to check
> > that now.
> >
> > But this is from my perl version. In your case for "No statements" the
> > value for $! and $@ was ^I.
>
> Maybe this is a syslog oddity? I've never seen $! or $@ getting set
> to "^I" ("\t"), so I don't think this is their actual value.
Ahh ^I = \t, then I understand. Yes that is likely a syslog oddity.
> > I can provide some testing code to you if you want so we can determine
> > the table above for your perl version.
>
> I doubt it would be any different with Perl 5.8.8, which is what I'm
> running.
>
> Well, we could try setting $! to 0 before the do() call and checking
> ($! || $@) afterwards. If that doesn't work, then the debarchiver
That could be a solution, yes. I'll check that out.
> man-page would have to explain that there needs to be a final, true-
> valued statement in every config file.
True.
I'll come up with a solution.
I hope you do not see this log everytime now at least. :)
Best regards,
// Ola
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