API question: slashes and backslashes

[Greg Ward]

I'm hard at work trying to get bfiles working on Windows.  I think my
biggest problem is that I just plain ignored the whole os.path.sep
issue -- I take filenames from dirstate or manifest and pass them to
the OS, and I naively expected filenames from the command line to make
sense in dirstate tests.  The latter caused actual bugs, which I have
crudely fixed with

  filename.replace(os.path.sep, '/')

in a few places, but that feels wrong.

The other thing that feels wrong is passing paths like

  c:\src\myproject/.hgbfiles/bigfile

to the OS.  Lucky for me Windows handles those paths, but I feel like
I'm skating on thin ice.  I generally get those sort of paths from
repo.wjoin().

What's the right way?  I've stumbled across util.pathto(), but it
doesn't feel like a general solution -- e.g. it's fine for taking a
path from the dirstate and generating an OS path, in certain
circumstances.  Consider this code, a simplified excerpt from the
'bfremove' command (remove a big file as long as it's not modified):

  modified1 = [...status of big files...]
  modified2 = repo.status(...)
  for standin in dirstate.walk(matcher):         # e.g. ".hgbfiles/foo/bar"
    filename = _split_standin(filename)         # return "foo/bar"
    if not (filename in modified1 or standin in modified2):
      os.unlink(repo.wjoin(filename))

modified1, modified2, standin, and filename all use Unix slash,
because they are all based on dirstate.  But then I need an actual
concrete filename that I can pass to os.unlink(), hence the
repo.wjoin() call.  But that will return something like

  c:\src\myproject\foo/bar

which is where I feel like I'm skating on thin ice.  So what *should*
I pass to repo.wjoin(), if not a filename from dirstate?

Thanks --

Greg