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

Beman Dawes wrote:

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At 01:02 AM 5/6/2003, richard_fanta wrote:

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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

richard_fanta wrote: dir_it.

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Can someone kindly tell me why this was removed? It's highly

useful,

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and part of every filesystem that I've seen.

ISO/IEC 9660:1999 filesystems don't supply a "last access" time stamp, perhaps because the original uses were on write-once media.

Which filesystems adhere to this spec other than CD-ROMs?

Many DVDs use this too, but for most purposes they're basically just higher-capacity CDs.

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Perhaps we should do more to support attribute query within the main

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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?

Other options: -For ISO 9660 filesystems, use the time created as the "last access" time stamp. -Throw a "FeatureNotSupportedException" or somesuch.

Then the feature won't be at all portable, and might as well not be supported at all. Access times are far from a universal OS feature, 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. Note that Windows NT maintains access times at quite a low resolution, to reduce this cost.