Re: [boost] Filesystem Library: Formal Review

From: Vladimir Prus (ghost_at_[hidden])
Date: 2002-09-18 03:07:18

Beman Dawes wrote:
> At 10:26 AM 9/17/2002, Volodya wrote:
> 
>  >This works nice here, but in a more complex example:
>  >
>  >     path base("/home/ghost", system_specific);
>  >     path p("a/b/c/d", system_specific);
>  >
>  >How do I join base with p?
> 
> I'm not sure what you mean by "join".  If the result you want is 
> "/home/ghost/a/b/c/d", then base<<p will do it.  If you want 
> "/home/a/b/c/d", then use base.branch()<<p.
> 
> If the result you want is something else, let me know.
> 
> Do I need to manually split p in components?
>  >
>  >     path base("/home/ghost", system_specific);
>  >     path p("/a/b/c/d", system_specific);
>  >
>  >Here, even if I manage to split 'p' into components, what will they be?
>  >I guess, "", "a", "b", "c", "d".
> 
> You can use path::begin() and path::end() to get iterators for the 
> sequence.  Iteration would return std::strings "/", "a", "b", "c", "d".
> 
> But that is only provided as a fall back to meet unusual needs. I don't 
> think you should need to do that for join().  But you need to give me 
> examples of what you expect the join() output to be. Is it just 
> concatenation or does it drop, merge, or otherwise modify some elements?

Speaking terms of posix paths, I want

     join("/home/ghost", "a/b") = "/home/ghost/a/b"
     join("/home/ghost", "/a/b") = "/a/b"

Without this functionality, I see no way to handle both relative and 
absolute paths in user input.

If I modify the program I recently posted to use 'system_specific' as it 
should:

     int main()
     {
         fs::path p1("/home/ghost", fs::system_specific),
                  p2("/a/b/c", fs::system_specific);

         cout << (p1 << p2).file_path() << "\n";
     }
It outputs "/home/ghost/a/b/c" --- the leading slash in p2 has no effect 
on output.

- Volodya