John E. Malmberg wrote:
Michael G Schwern wrote:
Is it correct that File::Spec::VMS->canonpath('[]') returns ''? This
is an explicit clause in File::Spec::VMS::canonpath().
$path =~ s/\[\]// unless $path eq '[]'; # [] ==>
No other File::Spec variation does this, they all return the
equivalent cwd.
Just tried it.
$ perl -mFile::Spec -e "print File::Spec::VMS->canonpath('[]')"
[]
Look again at the above rule, it already does what you want.
Must be a bug in 3.01 then. Yep, it doesn't have that unless clause.
This makes File::Spec->canonpath( File::Spec->curdir ) difficult to
use as now you have to carefully distinguish between false and
undefined to see an error.
Actually that brings up a different issue that was discussed on the
vmsperl list. You see '' is a valid file specification on VMS in VMS
file spec format.
What does it mean? Is it a synonym for cwd?
So undef is the only way to indicate an error. And it should be that
way on other platforms for consistency.
Making false or empty string a valid return value and only undef to indicate
an error makes interfaces really hard to use. File::Spec is already really
hard to use, so I'd like some way to reverse that.
But it's moot if canonpath is no longer returning [] as an empty string.
On a related note, unlike all the other File::Spec variants
File::Spec->catdir('', 'some', 'dir') does not produce an absolute
path. It does the opposite and produces a relative one. In fact, I
can't see how to make an absolute path on VMS with catdir().
You can not, you need to use catpath to make an absolute path. I do not
know if that is a bug or a feature.
So lets look on Microsoft Windows:
C:\tools>perl -mFile::Spec -e "print File::Spec->catdir('','foo','bar')"
\foo\bar
It looks to me that this is a bug. Both Microsoft Windows and VMS have
volume name components, so the routines should work similar.
At a guess I'd say it's to take into account that '' means something on VMS.
In the interest of compatibility, it should be ok to make an exception for an
empty string as the first directory in the list.
While changing this could be seen as breaking compatibility, the
catdir() behavior is tested in t/Spec.t, these differences in behavior
add to the difficulty of writing portable code for VMS. I'd see
making writing compatible code easier a greater priority than
maintaining a historical incompatibility.
From what I have been doing to get tests to pass on VMS, I have found
that a lot of the if $^O eq 'VMS' code is to work around such
inconsistencies. How much code is really expecting them to exist is
unknown.
I was thinking more of code written by VMS natives for VMS. I think
non-natives will be quite happy of any opportunity to throw out VMS exceptions.
I plan to start looking at these more in the future. Right now I am
fighting with getting gnu tar 1.19 to run on VMS so I can figure out why
Module::Build is not able to read a tarball that it creates using
Archive::Tar.
Ouch.
--
But there's no sense crying over every mistake.
You just keep on trying till you run out of cake.
-- Jonathan Coulton, "Still Alive"
