From: Robert Klemme <bob.news@...>
Date: 2004-04-30T23:39:01+09:00
Subject: Re: File.expand_path(__FILE__)


"John Platte" <john.platte@nikaconsulting.com> schrieb im Newsbeitrag
news:81CD2517-9AB0-11D8-82AE-000A95EB0812@nikaconsulting.com...
> The OP yawns and wakes up to a big thread that has sprouted up where he
> posted his little codeling...
>
> On 2004 Apr 30, at 6:39, Robert Klemme wrote:
>
> >> I wonder why __FILE__ isn't an absolute path. Relative paths is
> >> just too fragile.
> >>
> >>
> >> Proposal:  make __FILE__ an absolute path.
> >> That would make __FILE__ robust to Dir.chdir.
> >>
> >>
> >> Any thoughts on this proposal?   fore or against
>
> That was my expectation. I really don't understand why __FILE__ would
> be relative. I did a lot of work in PHP before coming to Ruby, and PHP
> uses an absolute path in its __FILE__, which is a wonderful thing when
> trying to create programs that are robust against odd web server
> configurations.
>
> I see Perl uses relative paths for both __FILE__ and $0...and since a
> lot of Ruby scripts use "if __FILE__ == $0", those two should keep
> following the same policy. So I don't expect that behavior to change
> for my odd little case.

.... or operators are overloaded to ensure proper behavior.

> Might there be another place to put this absolute path? (Or might one
> exist already?) PHP defines a global $SCRIPT_FILENAME...
>
> > Slightly against, because
> >
> > - it's easily fixed
>
> but obviously from the head-scratching on this thread, the current
> behavior at least threatens POLS.
>
> > - you loose information: there might be situations where the script
> > wants
> > to know the exact path it was invoked with.
>
> That seems like more of a special case to me than knowing exactly where
> we live in the filesystem, but I'll admit that if Ruby got this far
> with this behavior, maybe I'm not in the majority.

Both may be true. :-)

> > - most of the time (when invoked from the shell via path expansion)
> > scripts are invoked with an absolute path anyway.
>
> My situation: I was invoking a utility script from Vim's shell, and it
> had a bug that dumped output in the wrong directory. As I hacked a fix,
> somehow I wound up with code that triggered the unexpected behavior I
> posted about (I apologize for not pointing out which part was
> unexpected).
>
> Whatever the solution, I want it to be easy to get an authoritative
> absolute path for the current file from Ruby; I'd strongly prefer that
> it not be fragile to chdirs, since that's a side effect that reduces
> flexibility.
>
> Surely there's an existing solution to this within Ruby or Perl or some
> other language?

See my other post:

# at the top of script
FILE = File.expand_path( __FILE __ )

> Thanks to the other posters for the workaround(s) and explanation.

We love to bang our heads on simple looking but difficult to solve
problems. :-)

    robert