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

[Damien Doligez <damien.doligez@inria.fr>]

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