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<DIV><FONT face=Arial size=2>Avi Bryant is currently working on a port of <A
href="http://www.chronos-st.org/">Chronos</A> to Squeak. He has </FONT><A
href="http://map.squeak.org/package/46b5731f-5112-4157-94d3-d40c4ed8304d"><FONT
face=Arial size=2>published a Monticello package to SqueakMap</FONT></A><FONT
face=Arial><FONT size=2> that contains a very preliminary port. <SPAN
class=453205403-25022006> It is very much a "work in progress." When Avi is
satisfied that the port is sufficiently functional and stable, he will make a
general announcement to that effect. No promises have been made with
respect to when a version suitable for general use may become available, nor is
there any commitment to provide all the same functionality as is available from
the VisualWorks version. Of course, nothing prevents others from contributing
improvements/enhancements in addition to whatever Avi
publishes.</SPAN></FONT></FONT></DIV>
<DIV><FONT face=Arial><FONT size=2><SPAN
class=453205403-25022006></SPAN></FONT></FONT> </DIV>
<DIV><FONT face=Arial><FONT size=2><SPAN class=453205403-25022006>Initially, Avi
does not plan to port the Chronos Time Zone Compiler to Squeak. Tthe
Chronos Time Zone Compiler is used to generate the <A
href="http://www.chronos-st.org/downloads/time-zones.zip">Chronos Time Zone
Repository</A> from the information provided by the <A
href="http://www.twinsun.com/tz/tz-link.htm">Olson Time Zone Database</A>. Since
the <A href="http://www.chronos-st.org/downloads/time-zones.zip">Chronos Time
Zone Repositor</A>y a) is available from the <A
href="http://www.chronos-st.org/">Chronos web site</A>, and b) is usable "as is"
by any Smalltalk implementation (in fact, it would be usable by any programming
language, given a sufficiently powerful time zone implementation written in that
language,) that's not that big of an issue.</SPAN></FONT></FONT></DIV>
<DIV><FONT face=Arial><FONT size=2><SPAN
class=453205403-25022006></SPAN></FONT></FONT><FONT face=Arial><FONT
size=2><SPAN class=453205403-25022006></SPAN></FONT></FONT> </DIV><FONT
face=Arial><FONT size=2><SPAN class=453205403-25022006>
<DIV><SPAN class=453205403-25022006><FONT face=Arial size=2>It's only recently
that I have become at all familiar with Avi's work. Initially, I only knew
he was one of the principal authors of Seaside. <A
href="http://map.squeak.org/accountbyid/04ec7571-cb7e-47ea-b1fc-218f7ec45adc">But
he's done much more than just that</A> (although Seaside is impressive
enough by itself.) </FONT></SPAN></DIV>
<DIV><SPAN class=453205403-25022006><FONT face=Arial
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=453205403-25022006><FONT face=Arial size=2>I am very
appreciative of the contributution Avi is making towards porting Chronos to
Squeak.</FONT></SPAN></DIV>
<DIV> </DIV>
<DIV><STRONG>Fair warning</STRONG>: As </SPAN>of Sat, 25 Feb 2006 03:31:56 +0000
(Universal Time,) the version on SqueakMap will not work "as is" in versions of
Squeak from 3.7 onward (you can load it, but if you execute the
initialization/installation "do it" that the pop-up Transcript window suggests,
you will then be unable to either save the image or compile any
methods.) <SPAN class=453205403-25022006> The problem is caused by the fact
that the installation procedure (as implemented in the version currently
available from SqueakMap) redefines both DateAndTime and Duration so that they
are aliases for the Chronos classes Timepoint and ScientificDuration
(respectively,) in place of the native Chronology classes named DateAndTime and
Duration (and this issue is precisely why I chose not to use the names
"DateAndTime" and "Duration" as class names.) </SPAN>This problem can be
fixed<SPAN class=453205403-25022006> if, before evaluating the
'ChronosEnvironment install' "do it" as suggested, </SPAN>the
following <SPAN class=453205403-25022006>class </SPAN>method<SPAN
class=453205403-25022006> is first implemented</SPAN>: </FONT></FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2><STRONG>ChronosSqueakEnvironment
class>>setProtectedGlobalVariables</STRONG> <BR><SPAN
class=453205403-25022006> </SPAN>ProtectedGlobalVariables :=
Set with: #ScaledDecimal with: #DateAndTime with: #Duration. </FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial><FONT size=2><SPAN class=453205403-25022006>Avi is using
Squeak 3.6 to do the porting work. The Chronology library did not become
part of standard Squeak until version 3.7, and so there is no issue raised by
(re)defining the globals DateAndTime and Duration as global aliases for
Timepoint and ScientificDuration (respectively) in versions of Squeak prior
to 3.7. That may well be why Avi is using Squeak 3.6 to do the port.
(Squeak badly needs a mechanism to more elegantly handle issues such as this
one.)</SPAN></FONT></FONT></DIV>
<DIV><FONT face=Arial><FONT size=2><SPAN
class=453205403-25022006></SPAN></FONT></FONT> </DIV>
<DIV><FONT><FONT face=Arial><FONT size=2><SPAN class=453205403-25022006>Note
that the </SPAN>version currently <SPAN class=453205403-25022006>available
from</SPAN> SqueakMap has not been given the ability to access
files--<STRONG>so it can't <SPAN class=453205403-25022006>retrieve
</SPAN>any time zones from the </STRONG></FONT></FONT><A
href="http://www.chronos-st.org/downloads/time-zones.zip"><FONT face=Arial
size=2><STRONG>Chronos Time Zone Repository</STRONG></FONT></A><SPAN
class=453205403-25022006></SPAN><FONT face=Arial><FONT size=2>,<SPAN
class=453205403-25022006> and therefore Olson time zone keys such as
'Americal/Los_Angeles', 'Europe/Paris' and 'Asia/Tokyo' cannot be used to
identify a time zone</SPAN>. Nor <SPAN class=453205403-25022006>is there
any </SPAN>code that makes any attempt to determine the local time zone from the
host operating system, nor any code that provides any locale
information. </FONT></FONT></FONT></DIV>
<DIV><FONT><FONT face=Arial><FONT size=2></FONT></FONT></FONT> </DIV>
<DIV><FONT><FONT face=Arial><FONT size=2><SPAN
class=453205403-25022006>Consequently, </SPAN><SPAN class=453205403-25022006>the
Chronos system time zone simply defaults to Universal Time (which is what the
native Chronology library does also, so at least you're no worse off than you
were before.) Nevertheless, you can still do quite a bit.
</SPAN></FONT></FONT></FONT><FONT><FONT face=Arial><FONT size=2><SPAN
class=453205403-25022006>For example, after loading and properly initializing
Chronos, you can evaluate the following expression to set the Chronos system
time zone so that it matches the zone rules that have been in effect since 1996
for CET/CEST (Central European Time):</SPAN></FONT></FONT></FONT></DIV>
<DIV><FONT><FONT face=Arial><FONT size=2><SPAN
class=453205403-25022006></SPAN></FONT></FONT></FONT> </DIV>
<DIV><FONT><FONT face=Arial><FONT size=2><SPAN
class=453205403-25022006>
(ChronosTimezone<BR> key:
#'Europe/Berlin' name: #'Central European
Time'</SPAN></FONT></FONT></FONT></DIV>
<DIV><FONT><FONT face=Arial><FONT size=2><SPAN
class=453205403-25022006>
initialOffset: (ScientificDuration hours: 1) withAbbreviation:
#CET <BR>
until: (WeekOfMonthDayOfWeek month: 3 week: 0 dayOfWeek: 1) "The 'zeroeth
week' means the last week of the month"</SPAN></FONT></FONT></FONT></DIV>
<DIV><FONT><FONT face=Arial><FONT size=2><SPAN
class=453205403-25022006>
at: (TimeOfDay hour: 1 minute: 0 second: 0) relativity:
#universal</SPAN></FONT></FONT></FONT></DIV>
<DIV><FONT><FONT face=Arial><FONT size=2><SPAN
class=453205403-25022006> thenOffset:
(ScientificDuration hours: 2) withAbbreviation:
#CEST <BR>
until: (WeekOfMonthDayOfWeek month: 10 week: 0 dayOfWeek: 1)
</SPAN></FONT></FONT></FONT></DIV>
<DIV><FONT><FONT face=Arial><FONT size=2><SPAN
class=453205403-25022006>
at: (TimeOfDay hour: 1 minute: 0 second: 0) relativity:
#universal)</SPAN></FONT></FONT></FONT></DIV>
<DIV><FONT><FONT face=Arial><FONT size=2><SPAN
class=453205403-25022006>
beSystem</SPAN></FONT></FONT></FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><SPAN class=453205403-25022006><FONT face=Arial size=2>Then, you can
evaluate "Timepoint now" to see the current time. And if you find
yourself in Madrid, Paris, Berlin or Amsterdam, the answer will even be
correct. However, due to the fact that the Squeak system clock reports
local time, setting the Chronos system time zone has no effect on what is
displayed when "Timepoint now" is evaluated. It only changes the results
of evaluating "Timepoint utNow." On a system whose clock reported
Universal Time, the situation would be reversed.</FONT></SPAN></DIV>
<DIV><SPAN class=453205403-25022006><FONT face=Arial
size=2></FONT></SPAN> </DIV>
<DIV><SPAN class=453205403-25022006><FONT face=Arial
size=2>--Alan</FONT></SPAN></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
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