Re: [Ocaml-lib-devel] Unzip module and filesystems

[Sylvain LE G. <syl...@po...>]

Hello,

On Sat, Jul 24, 2004 at 02:01:29AM +0300, Jere Sanisalo wrote:
> On Fri, Jul 23, 2004 at 10:09:32PM +0200, Nicolas Cannasse wrote:
> >The Unzip module is now part of ExtLib !
> >You can deflate your TGZ and ZIP with pure OCaml code only !
> >Enjoy,
> 
> Cool, thanks!
> 
> I've still to see your code in the CVS (does sourceforge always have a delay
> after commit for the changes to show up?) but a few questions. So you have
> unzip, how about a zip? It's always handy to pack stuff as well.
> 
> And how far does the current module go? Can it unpack whole zip files with
> several files in them?
> 
> Which brings me to another curiosity I've been having. After looking at the
> ocaml core library I was missing abstract files (so I could implement my
> own, given an interface). Well, Extlib has that and great. But how about an
> abstract filesystem? Something along the lines of:
> ---
> class base_filesys :
> 	object
> 	method exists : string -> bool
> 	method size : string -> int
> 
> 	method chdir : string -> unit
> 	method cwd : unit -> string
> 	end
> 
> class ['a] i_filesys :
> 	object
> 	inherit base_filesys
> 
> 	method open_in : string -> 'a
> 	end
> 
> class ['a] o_filesys :
> 	object
> 	inherit base_filesys
> 
> 	method delete : string -> unit
> 
> 	method open_out : string -> 'a
> 	end
> 
> class ['a,'b] io_filesys :
> 	object
> 	inherit ['a] i_filesys
> 	inherit ['b] o_filesys
> 	end
> ---
> That way you could do easy wrappings for filesystems. Useful things like:
>  - Use a ZIP as a filesystem (input only if you please)
>  - Use remote filesystem
>  - Implement sandboxing (filesystem inside a filesystem, like prevent the
> application accidentally accessing some part outside the given directory)
> 

Well, i currently maintain a library which is called ocaml-fileutils. It
implements most operation you describe for real filesystem ( size = du,
exists = test Exist, cwd = pwd, delete = rm , in other word, take a look 
a the GNU fileutils ).

I was think of implementing a tar module for navigating tar archives,
and to give a model to expand it to anything else...

However, i don't use object oriented design ( i don't like this kind of
design )...

If you are interested in generating a tar navigator, please go ahead,
the library is made for extension ( if you want to extend, you will need
to use the module typing of the FileUtil module ).

Kind regard
Sylvain Le Gall

ps : http://www.carva.org/sylvain.le-gall/ocaml-fileutils.html