catfile/catdir collapses two leading slashes //

repellent has asked for the wisdom of the Perl Monks concerning the following question:

use File::Spec::Functions qw(catfile splitdir);

my @pathnames = splitdir '//special/semantic//path/definition';

my $path1 = catfile @pathnames;   # '/special/semantic/path/definition
+'
my $path2 = join '/', @pathnames; # '//special/semantic//path/definiti
+on'
[download]

But in Files and Filesystems:

Don't assume that in pathnames you can collapse two leading slashes // into one: some networking and clustering filesystems have special semantics for that. Let the operating system to sort it out.

What gives?

Comment on catfile/catdir collapses two leading slashes // Select or Download Code

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Re: catfile/catdir collapses two leading slashes // by ikegami (Patriarch) on Sep 17, 2008 at 18:25 UTC
Since File::Spec::Functions is system specific, the warning ("Don't assume ...") doesn't apply. Since you are using a unix system, "//" can be collapsed, and you get `/special/semantic/path/definition` [download] Since I use a Windows system, leading "\\" is special, and I get `\\special\semantic\path\definition` [download]	[reply] [d/l] [select]
Re^2: catfile/catdir collapses two leading slashes // by repellent (Priest) on Sep 17, 2008 at 20:31 UTC
Then I would suggest Files and Filesystems be updated. After all, it did mention "two leading slashes". I was also confused, because it mentioned "networking and clustering filesystems". These filesystems are not platform-specific. Shouldn't caution be taken every time, since a *nix system could potentially access a Windows network FS?	[reply]
Re^3: catfile/catdir collapses two leading slashes // by ikegami (Patriarch) on Sep 17, 2008 at 22:20 UTC
It's only used by the volume portion of UNC paths. If you were to mount a Windows share onto a unix system, I don't see why you'd use "\\" (or "//") anywhere. For example, if `\\server\docs` was mounted as `/mount/docs`, I presume `\\server\docs\some\path` would be addressed as `/mount/docs/some/path`. "Files and Filesystems" is correct. You shouldn't assume you can't. That doesn't mean you never can.	[reply] [d/l] [select]
Re: catfile/catdir collapses two leading slashes // by haoess (Curate) on Sep 17, 2008 at 07:16 UTC
The name of a directory is not the same as its pathname, so why don't you use `splitpath` and `catpath`? -- Frank	[reply] [d/l] [select]
Re^2: catfile/catdir collapses two leading slashes // by repellent (Priest) on Sep 17, 2008 at 07:37 UTC
Sure. But let's not stray off-topic :) `use File::Spec::Functions qw(catdir catpath splitdir splitpath); my ($volume, $directories, $file) = splitpath '//special/semantic//pat +h/definition'; my @dir = splitdir $directories; my $dir1 = catdir @dir; # '/special/semantic/path' my $dir2 = join '/', @dir; # '//special/semantic//path/' my $path1 = catpath $volume, $dir1, $file; # '/special/semantic/path/d +efinition' my $path2 = catpath $volume, $dir2, $file; # '//special/semantic//path +/definition'` [download] The name of a directory is not the same as its pathname There's always confusion with file nomenclature. See File system nomenclature. Death to path!	[reply] [d/l]