[boost] Re: Re: Re: [filesystem] status() if neither file nordirectory?

From: Beman Dawes (bdawes_at_[hidden])
Date: 2005-05-08 20:05:46

"Peter Dimov" <pdimov_at_[hidden]> wrote in message 
news:00a201c55418$585bb2c0$6401a8c0_at_pdimov2...
> Beman Dawes wrote:
>
>>> A hypothetical OS that allows directories to be opened with an
>>> ifstream may reasonably answer true to both is_stream(p) and
>>> is_directory(p). Or maybe not. :-)
>>
>> I think not. Dividing the world into non-overlapping categories is
>> much easier:-)
>
> It's only easier until an example comes up that doesn't fit the scheme, so 
> you are forced to invent meta-categories (also known as "hacks" in some 
> category theory circles) such as "other". :-)
>
> "Capability bits" are cleaner. Is it openable with ifstream? file_bit. Is 
> it iteratable with directory_iterator? directory_bit. Does it exist? 
> !not_found_bit.

I'm only partially convinced. How useful is knowing that you can ifstream a 
directory? The only cases I can think of are so system specific that I have 
trouble seeing them in the context of Boost.Filesystem.

> When a socket is thrown your way, you just run it by the list and conclude 
> that no bit needs to be set.

But that is about the same as having an other_flag, except that the name is 
0 instead of other_flag. Giving it a name makes it more obvious that a 
return from status() may not have any of the other bits set

--Beman