[R] Tracking when an object/function was modified

[Duncan Murdoch]

On 3/8/2007 9:06 AM, Duncan Murdoch wrote:
> On 3/8/2007 8:54 AM, Mona Kanaan wrote:
>> Dear R-users,
>> 
>> If I would like to track the date when an R-object (specifically  an R- 
>> function) was modified, how can I achieve that? Furthermore, how can I 
>> sort these objects based on date  modified?
> 
> R doesn't give you a way to do that.  Objects have no timestamps on them.
> 
> Adding a timestamp would be quite hard; it would need to be done at a 
> very low level.  For example, you might do this:
> 
> 9 AM:
> 
> f <- function() 1
> 
> 10 AM:
> 
> g <- function() 2
> 
> 11 AM:
> 
> f <- g
> 
> Now should the timestamp on f be 11 AM or 10 AM?  I think 11 AM makes 
> more sense, but that implies modifying the way assignments are done.  If 
> 10 AM would be good enough, you'd only need to modify the way "function" 
> works (and some other functions that modify functions, e.g. body<-, etc.)
> 
> I would say this is not worth attempting.  It's better to keep your 
> function definitions in source form (e.g. in the source of a package, or 
> just in a script that you'll source()), and then use tools external to R 
> to track modifications.  Subversion is very good at that.

Sorry, one addition here:

In R 2.5.0, you'll have the option of keeping source references when you 
use source() or parse(), and those include timestamps on files when 
that's where the source comes from.

Duncan Murdoch