[REBOL] Re: Creating unique ID's?
From: joel:neely:fedex at: 16-Jul-2002 14:35
Hi, Gregg,
Gregg Irwin wrote:
> <<
> I need to create ID's which are unique over even when they are created
> on different machines, or several poeple on the same machine, etc. Does
> anyone have a better idea than
>
> unique-id: join join system/user/email system/network/host now/precise
> >>
>
> I guess that depends on *how* unique they need to be. For example, if you
> call this twice in a row, you'll very likely get the same ID...
>
It depends on your computer!!!
On a real computer/OS with a microsecond clock, even consecutive
evaluations of NOW/TIME/PRECISE yield different values...
>> reduce [now/time/precise now/time/precise now/time/precise]
== [14:42:25.950478 14:42:25.950988 14:42:25.951521]
>> reduce [now/time/precise now/time/precise now/time/precise]
== [14:42:30.728039 14:42:30.728536 14:42:30.729006]
>> reduce [now/time/precise now/time/precise now/time/precise]
== [14:42:31.277009 14:42:31.277474 14:42:31.27795]
>> reduce [now/time/precise now/time/precise now/time/precise]
== [14:42:31.743064 14:42:31.743529 14:42:31.744091]
... although that doesn't hold true for Visual MS-DOS. ;-)
-jn-
