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Postings from October 2011
On Thu Aug 04 03:16:05 2011, jpl@research.att.com wrote:
> Ed Avis <eda@waniasset.com> noted:
>
> > Unfortunately, that's a "feature", not a "bug". Spaces delimit
> separate
> > >patterns, and there must be a ton of scripts that rely on that
> behavior
> > >("*.c *.h")
> There must be lots of programs that rely on that. But are they
> not outnumbered
> by the programs which rely on glob working for general filenames,
> e.g.
>
> $wildcard = shift @ARGV;
> @files = glob($wildcard);
>
> OK, so that code is broken and has always been broken. But it's
> not uncommon,
> as a quick search turns up:
>
>
<http://www.google.com/codesearch#search/&q=glob\%28\$%20lang:^perl$&type=cs>
>
> It's all rather unfortunate, since the '*.c *.h' behaviour can
> easily be had by
> doing (glob('*.c'), glob('*.h')) instead, and was always more of
> an accidental
> side-effect of calling out to tcsh for the globbing.
>
>
> One reason this bug has gone (relatively) unnoticed for so long is
> that
> it doesn't happen in list context. So your example and many of the
> examples you cite will work just fine. It's scalar context that
> triggers the problem. There's some magic that I don't yet fully
> understand (and won't until I get back from vacation) that hands glob
> a
> second argument that can be used to identify which invocation is in
> play, so state can be maintained. It's there (using -MO=Deparse) when
> ':glob' is used
>
> use File::Glob (':glob');
> while (defined($_ = glob("$dir/*", 0))) {
> last if ++$entries > $max;
> }
> while (defined($_ = glob("$dir/*", 1))) {
> last if ++$entries > $max;
> }
>
> but not when it is missing
>
> use File::Glob (':globally');
> while (defined($_ = glob("$dir/*"))) {
> last if ++$entries > $max;
> }
> while (defined($_ = glob("$dir/*"))) {
> last if ++$entries > $max;
> }
>
> That seems totally backwards; it seems like the extra argument is
> essential for maintaining state to make scalar context act like an
> iterator, but it's ':glob' that is broken and everything else works.
File::Glob::glob explicitly ignores its second argument:
sub glob {
splice @_, 1; # don't pass PL_glob_index as flags!
goto &bsd_glob;
}
What you are seeing above is a B::Deparse bug, fixed in 5.14.0.
> My
> diffs point how to make things work with embedded space, but I'm not
> satisfied, because I don't really understand what's happening. Anyone
> should feel free to fix things while I'm vacationing:-) . -- jpl
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