[R] Age of an object?

Martin Maechler maechler at stat.math.ethz.ch
Wed Dec 14 10:47:14 CET 2005

>>>>> "Trevor" == Trevor Hastie <hastie at stanford.edu>
>>>>>     on Tue, 13 Dec 2005 12:51:34 -0800 writes:

    Trevor> It would be nice to have a date stamp on an object.

    Trevor> In S/Splus this was always available, because objects were files.

   [are you sure about "always available"? 
    In any case, objects were not single files anymore for a
    long time, at least for S+ on windows, and AFAIK also on
    unixy versions recently ]

This topic has come up before.
IIRC, the answer was that for many of us it doesn't make sense
most of the time: 

If you work with *.R files ('scripts') in order to ensure
reproducibility, you will rerun -- often source() -- these files,
and the age of the script file is really more interesting.
Also, I *always* use the equivalent of  q(save = "no") and
almost only use save() to particularly save the results of
expensive  computations {often, simulations}.

    Trevor> I have looked around, but I presume this information is not available.

I assume you will get other answers, more useful to you, which
will be based on a class of objects which carry an
'creation-time' attribute.  

Martin Maechler, ETH Zurich

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