[phobos] RFC: std.path

[Lars Tandle Kyllingstad]

On Sun, 2011-06-12 at 13:36 -0300, Jose Armando Garcia wrote:
> On Sun, Jun 12, 2011 at 12:59 PM, Lars Tandle Kyllingstad
> <lars at kyllingen.net> wrote:
> > On Sun, 2011-06-12 at 12:41 -0300, Jose Armando Garcia wrote:
> >> On Sun, Jun 12, 2011 at 12:15 PM, Lars Tandle Kyllingstad
> >> <lars at kyllingen.net> wrote:
> >> > On Sun, 2011-06-12 at 11:39 -0300, Jose Armando Garcia wrote:
> >> >> On Wed, Jun 8, 2011 at 4:29 PM, Lars Tandle Kyllingstad
> >> > These functions are from the old std.path, and I haven't made any
> >> > changes to them in my version.
> >> >
> >> > - toAbsolute()
> >> > - toCanonical()
> >> >
> >>
> >> In the comments where you say that it doesn't perform any IO you
> >> should add these functions.
> >
> > Does getcwd() perform any IO on Windows?  AFAIK, on POSIX it just
> > queries /proc/self/cwd, which is a virtual file.
> >
> 
> The way I look at IO is anything that is external to the process.
> Another way to thinking about it is that
> toAbsolute()'s and toCanonical()'s result is dependent on state
> outside of the process. While the rest of the templates/functions
> aren't.

The way I've interpreted the "no IO" principle of std.path is "no
disk/network IO", since those would come with an enormous performance
penalty as compared to in-memory operations.  But maybe you are right.


> >> Speaking of which can we add a template
> >> called normalize (maybe you can come up with a better name) that does
> >> what canonical does but doesn't make it absolute. E.g.:
> >>
> >> version(windows) assert(normilize("dir/file") == "dir\\file");
> >> version(windows) assert(normilize("dir/./file") == "dir\\file");
> >> //etc
> >
> > That sounds like a good idea.  Then I guess normalize("../foo") should
> > just return "..\\foo", i.e. leave the ".." unresolved?
> >
> 
> It is hard to resolve '..' without looking at the file system when
> considering soft/sym link due to multiple parents. if 'somedir' is a
> simlink "somedir/../" != ".".

That is a matter of choice, I guess.  In both bash and zsh, if I type

   cd some_dir/some_symlink/..

I end up in some_dir, regardless of where some_symlink is pointing.
That is how toCanonical() does things as well, and how I think
normalize() should work if I end up adding that.

-Lars