[R] time (or output of function) in the R prompt

[Thomas Lumley]

On Thu, 11 Apr 2002, Liaw, Andy wrote:

> Dear R-help,
>
> Would it be possible to have the "prompt" option accept a function, such as
> date()?  This way, I can easily deduce the elapse time of top level R
> expressions.  This would be similar to how Unix shells handle their prompt
> variables.

You can almost do this with the taskCallback Manager

> h <- taskCallbackManager()
> h$add(function(expr, value, ok, visible) {
		options(prompt=paste(date(),"> "));
		return(TRUE)},
       name="dateprompt")

Thu Apr 11 10:47:06 2002 > 1+1
[1] 2
Thu Apr 11 10:48:28 2002 >

I say `almost' because the time is updated only when you actually compute
something.  If you just press <return> it doesn't change. Apart from that
it works.


	-thomas

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