I use a forked Squeak 4.5 
If i do 
DateAndTime	 today 2016-11-20T00:00:00+01:00
DateAndTime	 today asUnixTime	 1479596400
DateAndTime	 fromUnixTime: 1479596400 2016-11-19T23:00:00+01:00

The intended use is for put it in FileName compatible to all OS

1479596400NameOfFile.extension

An example
  Go http://wiki.squeak.org/squeak/recent

Parsing the links and convert the html to objects
Then saving this objects gives

1477612800Environment initialize.obj
1477612800Environment withName aName.obj
1477612800Environment.obj
1478131200JSON.obj
1478131200SIXX.obj
1478131200STON.obj
1478476800Monticello Basics.obj
1478563200Seaside status November 2016.obj
1478563200Seaside.obj

If you do( DateAndTime fromUnixTime:1478563200) asDate gives 8 November 2016
I understand you point but the current implementation is enough to me.

Edgar

> On Nov 20, 2016, at 01:12, David T. Lewis <lewis at mail.msen.com> wrote:
> 
> On Fri, Nov 18, 2016 at 07:01:29PM +0100, Bert Freudenberg wrote:
>> 
>> On Fri, Nov 18, 2016 at 2:16 PM, Edgar De Cleene <edgardec2005 at gmail.com>
>> wrote:
>> 
>>> Fellows:
>>> I found useful add UnixTime at the beginning of file names for you have
>>> nnnFoo.etc what is compatible with different OS and you easily see ordered
>>> .
>>> 
>>> But I my image I do not have how convert this value to DateAndTime again.
>>> So i attach this just in case some could use it.
>>> 
>> 
>> Since we already have DateAndTime>>asUnixTime, having DateAndTime
>> class>>fromUnixTime: seems like a reasonable addition. Thank you!
>> 
>> - Bert -
> 
> Edgar's enhancement looks good to me also, but unfortunately it does not
> work due to a problem in DateAndTime class>>fromSeconds:, which is supposed
> to do this:
> 
>   DateAndTime class>>fromSeconds: seconds 
>       "Answer a DateAndTime since the Squeak epoch: 1 January 1901"
> 
> 
> If we agree that the Squeak epoch was supposed to have been defined relative
> to UTC, then #fromSeconds: is broken because it treats its argument as
> seconds since the "local Squeak epoch" (early Squeak VMs were built upon
> the faulty premise of using local time).
> 
> Because of this problem in #fromSeconds: we get the following (I am five
> hours from GMT):
> 
>   dt1 := DateAndTime now.
>   unixSeconds1 := dt1 asUnixTime.
>   dt2 := DateAndTime fromUnixTime: unixSeconds1.
>   unixSeconds2 := dt2 asUnixTime.
>   dt2 - dt1. ==> 0:04:59:59.890588
>   unixSeconds2 - unixSeconds1. ==> 18000
> 
> IMO, Edgar's method is correct and we should fix DateAndTime class>>fromSeconds:
> so that the argument is interpreted as seconds since the UTC Smalltalk epoch.
> 
> <OT>
> Note also that #asUnixTime truncates (or rounds?) to a whole second, which is
> reasonable given that Unix time(2) does the same thing. But it might deserve
> a method comment if that is the intended behavior. If the method was named
> #asPosixTime, then I might argue that the value should not be rounded or
> truncated.
> </OT>
> 
> Dave
> 
> 

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