Re: [Caml-list] RFC: basename, dirname, PR#4549

[Gerd Stolpmann <info@gerd-stolpmann.de>]

Hi,

I've done a lot of system programming in the past years, and I cannot
remember that I had to work around this small incompatibility.

Semantically, the POSIX specs are better, because only directories are
allowed to have trailing slashes, and if you want to get the basename of
"path/" you want the name of the directory in >99% of the cases. The
trailing slash has only the meaning that it is asserted that the path
refers to a directory. And operations like "basename" better ignore such
assertions.

There could be a problematic area, though: URLs. A trailing slash means
here a different resource. I don't know whether anybody is using
basename in this context.

Gerd

Am Dienstag, den 27.12.2011, 17:29 +0100 schrieb Damien Doligez:
> Hello,
> 
> I would like to get some comments from the OCaml community at large about
> the problem raised in http://caml.inria.fr/mantis/view.php?id=4549
> 
> In a nutshell, the problem is that our version of basename and dirname
> are not exactly the same as the Open Group's definition.
> 
> We can easily implement the standard behaviour for basename and dirname,
> and it seems desirable, but there is a catch: we will have to change
> the specification of the standard library slightly.
> 
> Currently, we specify this:
> 
>    [concat (dirname name) (basename name)] returns a file name
>    which is equivalent to [name]. Moreover, after setting the
>    current directory to [dirname name] (with {!Sys.chdir}),
>    references to [basename name] (which is a relative file name)
>    designate the same file as [name] before the call to {!Sys.chdir}.
> 
> With the Open Group basename and dirname, this becomes false for
> names that include some trailing slashes, because such slashes
> are removed by basename.  This means that a name "foo/bar/"
> becomes "foo/bar" when put through
>   [concat (dirname name) (basename name)]
> and opening "foo/bar" may succeed if it is a file, while
> opening "foo/bar/" would fail.
> 
> I would like to know if anyone relies on the precise behaviour
> documented in the standard library, and for everyone else, would
> you prefer the old behaviour or the new (standard) behaviour?
> 
> -- Damien
> 
>