RE: [Boost-Users] Re: Why isn't the "last access time" part of the filesystem library?

From: Ben Hutchings (ben.hutchings_at_[hidden])
Date: 2003-05-09 10:09:57

richard_fanta <richard.fanta_at_[hidden]>:
> --- In Boost-Users_at_[hidden], "Ben Hutchings" 
> <ben.hutchings_at_b...> wrote:
> > richard_fanta <richard.fanta_at_m...> wrote:
> > > Beman Dawes <bdawes_at_a...> wrote:
> > > > At 01:02 AM 5/6/2003, richard_fanta wrote:
> > > >  >Looking at the filesystem library and the attributes work in
> > > >  >boost-sandbox, I don't immediately see "last access time"
> > > >  >being available for a file or directory.
> > > >  >
> > > >  >"Last access time" was included in Dietmar Kuehl's original
> > > >  >dir_it.
> > > >  >
> > > >  >Can someone kindly tell me why this was removed?  It's highly
> > > >  >useful, and part of every filesystem that I've seen.
<snip>
> > > > Perhaps we should do more to support attribute query within the
> > > > main library, but I don't really think we should include any
> > > > that aren't reliably supported by at least POSIX, Windows, and
> > > > ISO-9660 systems.
> > > 
> > > Your point is well made.  However, it does seem odd that a
> > > feature that is useful for >95% of all typical usage shouldn't be
> > > in the library.
> > 
> > What does that figure refer to, if anything?
> 
> Typical application usage.  Yes, mileage can vary.
> 
> Out of the last 50 apps you wrote that did file access, how many 
> involved CD-ROMS/DVDs that were ISO 9660 filesystems?

I think most of them could quite happily have worked with files on
CD-ROMs, but then I tend to write general-purpose code rather than
very specific applications.  A few of them needed to know file
modification times.

<snip> 
> > and updates to them may be disabled because the volume is read-
> > only (whether or not the underlying medium is read-only) or
> > purely to avoid the cost of updating them.  
> 
> Even if the volume is read-only from one machine, it might still
> help to know when the file was last altered.
> 
> > Note that Windows NT maintains
> > access times at quite a low resolution, to reduce this cost.
> 
> Low resolution or not, it's there.  When the file changes, the 
> timestamp is updated.  That's information that many applications 
> would find useful.
<snip>

What you're talking about is the modification time, not the access
time.  I agree that *that* is useful and widely supported, but it's
not what you were originally asking for!