Re: [Ocaml-lib-devel] Filename and file manipulation

[<syl...@po...>]

Hello,

On Sun, Feb 01, 2004 at 10:54:27AM +0100, Nicolas Cannasse wrote:
> > Sometimes ago we were discussing about a possible library manipulation
> > filename and files.
> >
> > I have almost created it. I think it is pretty stable but i need
> > extended testing on different filename, and an expert eye on my code.
> >
> > You can find documentation and tarball here :
> > http://www.gallu.homelinux.org/~gildor/ocaml-fileutils/
> 
> Hello,
> 
> I had a look at SysPath. My first thoughs were that it's too much complex.
> It seems that in order to have multi OS library, you used several language
> features such as Functors , as well as a lexer plus a yacc parser for each
> system in order to parsing the paths. IMHO it's too heavyweight and the
> small differences ( drive letter and / against \ ) in path representation
> between systems should be handled with a maximal transparency.
> 
> Using functors to abstract something is nice if you're expecting the future
> users of your library to have the will to extend it further. I don't think
> it applies to this problem, since we already know well the 3-4 differents
> systems ( Unix , MacOS, Windows, Cygwin-? ) and there is an almost-zero
> probability that another system using a different path representation will
> be added to this list in the future...
> 
> Using a lexer and a yacc parser for parsing such easy things as paths is
> also - still IMHO - using a hammer to kick a mosquito. A simple custom
> lexer/parser such as the one I proposed in my original post should be enough
> and perhaps provide even better speed.
> In order to be KISS-compliant, I advise you to rewrote the whole SysPath
> using only one file and module.

Well, OK. You are right about the fact that is a bit complicated.
However, the difference doesn't lie only in separator. For example :
MacOS ":a" means for unix "./a" and "::a" means "./../a"...

For MacOS theres separator are context dependent. So i cannot apply
simple regexp for doing filename split... I can analyze the string and
adapt it to my need with String ( just like original implementation of
Flename ). But it is as heavy as lex/yacc. 

There is also the problem of escaped char...

To my mind, lex/yacc is kiss compliant. But it is only a point of view (
i use frequently this kind of construct because most of the time, when i
do a custom parser/lexer, it always finish to block me when i try to
extend it in any direction ). Concerning the speed, i think there is no
real difference between custom parser and yacc parser ( i will tend to
think that it is faster with yacc than with a custom parser ).

The code by itself (yacc+lex+interface)x(win32,unix,macOs,cygwin) + sysPath.ml
sysUtil.ml is not very long... And each module is KISS compliant. If i
merge all in one file, i will have something too complicated. 

Concerning other implementation, i think that one day i will add, some
others possibility, like URL et al. 

In fact, i think we do not agree on one thing : path and filename are
complicated too me -- maybe i am silly. You need to take in account a
lot of things to deals with this kind of things. 

> 
> SysUtil looks very good, I have no complaints about it :)
> 

At least, there is one good things ;-)

> Regards,
> Nicolas Cannasse
> 

Thanks for the report.
Kind regard
Sylvain LE GALL