[R] How to know created time of object in R?

[Alberto Monteiro]

Prof Brian Ripley wrote:
>
>> I would like to know the created time and date of specific object.
>> Is there any function for it?
> 
> There isn't even the concept.  Most objects in R are a collection of 
> SEXPRECs created at different times.  Suppose you create a data 
> frame out of existing columns, and then later change the names? What 
> does 'created' mean for the data frame?
> 
> In any case, none of the possibly relevant date-times is stored.
> 
I imagine that it could be possible to create a class that
would store the "creation time" of its objects... but I have
no idea how to do it (I think I could do it in C++, but I am
illiterate in R++ oops S4 classes).

Alberto Monteiro