Martin Maechler wrote: >>>>>>"Trevor" == Trevor Hastie <[EMAIL PROTECTED]> >>>>>> 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:
I remember it was discussed several times. I don't remember why it was considered too difficult to do. > 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}. OK, now let me give examples where having such an information would ease the work greatly: you have a (graphical) view of the content of an object (for instance, the one using the "view" button in R commander), or you have a graphical object explorer that has a cache to speed up display of information about objects in a given workspace (for instance, the SciViews-R object explorer). What a wonderful feature it will be to tell if an object was changed since last query. In the view, one could have a visual clue if it is up-to-date or not. In the object explorer, I could update information only for objects that have changed... > 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. Yes, but that would work only for objects designed that way, and only if the methods that manipulate that object do the required housework to update the 'last-changed' attribute (the question was about last access of an object, not about its creation date, so 'last-changed' is a better attribute here). If you access the object directly with, let's say, [EMAIL PROTECTED] <- newvalue, that attribute is not updated, isn't it? Best, Philippe Grosjean > Martin Maechler, ETH Zurich > > ______________________________________________ > R-help@stat.math.ethz.ch mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html > > ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html