From mvyver at gmail.com  Wed Feb  6 03:36:49 2008
From: mvyver at gmail.com (Mark Van De Vyver)
Date: Wed, 6 Feb 2008 19:36:49 +1100
Subject: [TZInfo-users] TzInfo timezone base question
Message-ID: <389c43e40802060036y2ec676e1g45e6016f962cd0dd@mail.gmail.com>

Hi,
Thanks for the work that has gone into making tzinfo available, and
for making it freely available!

I'm trying to figure out a way to obtain a Time instance that has a
'specific' timezone.  The twist is I just start with a time string.

For example

require 'tzinfo'

# Returns my time zone (GMT +11)
Time.parse("09:30").iso8601 # "2008-02-06T09:30:00+11:00"

What I'd like to be able to do is something like:

Time.parse("09:30", other_tz).iso8601

which would return the deired timezone, say:

"2008-02-06T09:30:00+5:00"

Is there a way to do this using tzinfo?

Appreciate any suggestions.

Cheers
Mark

From phil.ross at gmail.com  Wed Feb  6 08:43:12 2008
From: phil.ross at gmail.com (Philip Ross)
Date: Wed, 6 Feb 2008 13:43:12 +0000
Subject: [TZInfo-users] TzInfo timezone base question
In-Reply-To: <389c43e40802060036y2ec676e1g45e6016f962cd0dd@mail.gmail.com>
References: <389c43e40802060036y2ec676e1g45e6016f962cd0dd@mail.gmail.com>
Message-ID: <4ac540410802060543w688d5a8cwe5a33e5e23d2cbfb@mail.gmail.com>

On 06/02/2008, Mark Van De Vyver <mvyver at gmail.com> wrote:
> Hi,
> Thanks for the work that has gone into making tzinfo available, and
> for making it freely available!
>
> I'm trying to figure out a way to obtain a Time instance that has a
> 'specific' timezone.  The twist is I just start with a time string.
>
> Is there a way to do this using tzinfo?

Hi Mark,

The Ruby Time class only supports representing times in either UTC or
the local timezone of the system.

On Unix based architectures, the local timezone can be changed at
runtime by setting the TZ environment variable. This will affect all
Times constructed after changing the environment variable. For
example:

> ENV['TZ']='Australia/Melbourne'
=> "Australia/Melbourne"
> Time.parse("09:30").iso8601
=> "2008-02-07T09:30:00+11:00"
> ENV['TZ']='Asia/Karachi'
=> "Asia/Karachi"
> Time.parse("09:30").iso8601
=> "2008-02-06T09:30:00+05:00"

On Windows, changing the TZ environment variable has no effect (see
http://www.ruby-forum.com/topic/68570#88607).

Because of the limitations of the Time class, TZInfo always returns
UTC Time instances and ignores the timezone of Times that are passed
in.

Regards,

Phil

--
Phil Ross
http://tzinfo.rubyforge.org/ -- DST-aware timezone library for Ruby

From mvyver at gmail.com  Wed Feb  6 14:46:26 2008
From: mvyver at gmail.com (Mark Van De Vyver)
Date: Thu, 7 Feb 2008 06:46:26 +1100
Subject: [TZInfo-users] TzInfo timezone base question
In-Reply-To: <4ac540410802060543w688d5a8cwe5a33e5e23d2cbfb@mail.gmail.com>
References: <389c43e40802060036y2ec676e1g45e6016f962cd0dd@mail.gmail.com>
	<4ac540410802060543w688d5a8cwe5a33e5e23d2cbfb@mail.gmail.com>
Message-ID: <389c43e40802061146g554f8178oc5ebaada252c307@mail.gmail.com>

Hi Philip,

Thanks for the prompt response....

On Feb 7, 2008 12:43 AM, Philip Ross <phil.ross at gmail.com> wrote:
> On 06/02/2008, Mark Van De Vyver <mvyver at gmail.com> wrote:
> > Hi,
> > Thanks for the work that has gone into making tzinfo available, and
> > for making it freely available!
> >
> > I'm trying to figure out a way to obtain a Time instance that has a
> > 'specific' timezone.  The twist is I just start with a time string.
> >
> > Is there a way to do this using tzinfo?
>
> Hi Mark,
>
> The Ruby Time class only supports representing times in either UTC or
> the local timezone of the system.
>
> On Unix based architectures, the local timezone can be changed at
> runtime by setting the TZ environment variable. This will affect all
> Times constructed after changing the environment variable. For
> example:
>
> > ENV['TZ']='Australia/Melbourne'
> => "Australia/Melbourne"
> > Time.parse("09:30").iso8601
> => "2008-02-07T09:30:00+11:00"
> > ENV['TZ']='Asia/Karachi'
> => "Asia/Karachi"
> > Time.parse("09:30").iso8601
> => "2008-02-06T09:30:00+05:00"

Thanks for the clarification, so there is no way to achieve a similar
effect using tzinfo.

> On Windows, changing the TZ environment variable has no effect (see
> http://www.ruby-forum.com/topic/68570#88607).
>
> Because of the limitations of the Time class, TZInfo always returns
> UTC Time instances and ignores the timezone of Times that are passed
> in.

OK this is where I got a little confused - apologies if this is
obvious, so it seems to do what I want I can't use 'parse', but
instead will have to extract the hrs and minutes, then use:

tz = TZInfo::Timezone.get(source_tz)
src_time_as_utc = tz.local_to_utc(Time.local(2005,8,29,src_hrs,src_mins,0))

Thanks for the clarification.

Regards
Mark

> Regards,
>
> Phil
>
> --
> Phil Ross
> http://tzinfo.rubyforge.org/ -- DST-aware timezone library for Ruby
>

From phil.ross at gmail.com  Wed Feb  6 15:11:39 2008
From: phil.ross at gmail.com (Philip Ross)
Date: Wed, 6 Feb 2008 20:11:39 +0000
Subject: [TZInfo-users] TzInfo timezone base question
In-Reply-To: <389c43e40802061146g554f8178oc5ebaada252c307@mail.gmail.com>
References: <389c43e40802060036y2ec676e1g45e6016f962cd0dd@mail.gmail.com>
	<4ac540410802060543w688d5a8cwe5a33e5e23d2cbfb@mail.gmail.com>
	<389c43e40802061146g554f8178oc5ebaada252c307@mail.gmail.com>
Message-ID: <4ac540410802061211r54600c6fjefaeec756813b511@mail.gmail.com>

On 06/02/2008, Mark Van De Vyver <mvyver at gmail.com> wrote:
> On Feb 7, 2008 12:43 AM, Philip Ross <phil.ross at gmail.com> wrote:
> > On Unix based architectures, the local timezone can be changed at
> > runtime by setting the TZ environment variable. This will affect all
> > Times constructed after changing the environment variable. For
> > example:
> >
> > > ENV['TZ']='Australia/Melbourne'
> > => "Australia/Melbourne"
> > > Time.parse("09:30").iso8601
> > => "2008-02-07T09:30:00+11:00"
> > > ENV['TZ']='Asia/Karachi'
> > => "Asia/Karachi"
> > > Time.parse("09:30").iso8601
> > => "2008-02-06T09:30:00+05:00"
>
> Thanks for the clarification, so there is no way to achieve a similar
> effect using tzinfo.

There is no equivalent of the parse function in TZInfo. You could use
parse and do the following though:

tz = TZInfo::Timezone.get(source_tz)
src_time_as_utc = tz.local_to_utc(Time.parse("09:30" + " UTC", tz.now))

Adding " UTC" to the time forces it to be parsed as a UTC timestamp
and causes any daylight savings rules of the system timezone to be
ignored. TZInfo will still treat the time value as if it were in local
time (it ignores the timezone aspect of the Time).

Passing tz.now as the second argument to Time.parse is required in
order to make sure you are dealing with the correct date.

> OK this is where I got a little confused - apologies if this is
> obvious, so it seems to do what I want I can't use 'parse', but
> instead will have to extract the hrs and minutes, then use:
>
> tz = TZInfo::Timezone.get(source_tz)
> src_time_as_utc = tz.local_to_utc(Time.local(2005,8,29,src_hrs,src_mins,0))

This would work too. TZInfo will just read the year, month, day, hour,
minute and second of the Time passed to local_to_utc and ignore the
timezone. It doesn't matter if Time.local returns a different timezone
to source_tz.

I would use Time.utc instead of Time.local though. If you specified a
time that fell in a transition between standard and daylight savings
time of the system timezone, then you might get an unexpected result
with Time.local.

Regards,

Phil

--
Phil Ross
http://tzinfo.rubyforge.org/ -- DST-aware timezone library for Ruby

From mvyver at gmail.com  Wed Feb  6 15:29:30 2008
From: mvyver at gmail.com (Mark Van De Vyver)
Date: Thu, 7 Feb 2008 07:29:30 +1100
Subject: [TZInfo-users] TzInfo timezone base question
In-Reply-To: <4ac540410802061211r54600c6fjefaeec756813b511@mail.gmail.com>
References: <389c43e40802060036y2ec676e1g45e6016f962cd0dd@mail.gmail.com>
	<4ac540410802060543w688d5a8cwe5a33e5e23d2cbfb@mail.gmail.com>
	<389c43e40802061146g554f8178oc5ebaada252c307@mail.gmail.com>
	<4ac540410802061211r54600c6fjefaeec756813b511@mail.gmail.com>
Message-ID: <389c43e40802061229n5718a26el5734608b14fa24a9@mail.gmail.com>

Hi Philip,

On Feb 7, 2008 7:11 AM, Philip Ross <phil.ross at gmail.com> wrote:
> On 06/02/2008, Mark Van De Vyver <mvyver at gmail.com> wrote:
> > On Feb 7, 2008 12:43 AM, Philip Ross <phil.ross at gmail.com> wrote:
> > > On Unix based architectures, the local timezone can be changed at
> > > runtime by setting the TZ environment variable. This will affect all
> > > Times constructed after changing the environment variable. For
> > > example:
> > >
> > > > ENV['TZ']='Australia/Melbourne'
> > > => "Australia/Melbourne"
> > > > Time.parse("09:30").iso8601
> > > => "2008-02-07T09:30:00+11:00"
> > > > ENV['TZ']='Asia/Karachi'
> > > => "Asia/Karachi"
> > > > Time.parse("09:30").iso8601
> > > => "2008-02-06T09:30:00+05:00"
> >
> > Thanks for the clarification, so there is no way to achieve a similar
> > effect using tzinfo.
>
> There is no equivalent of the parse function in TZInfo. You could use
> parse and do the following though:
>
> tz = TZInfo::Timezone.get(source_tz)
> src_time_as_utc = tz.local_to_utc(Time.parse("09:30" + " UTC", tz.now))

Sorry I wasn't clearer, but in my case the time string 09:30 refers to
the source_tz, which is _not_ my local tz nor UTC, and this source tz
may change in different calls to the method I'm trying to write.  I'd
like to get a time object that is in the source_tz, but have abandond
this idea, and will settle for an iso8601 string that contains the
time in the source tz.

> Adding " UTC" to the time forces it to be parsed as a UTC timestamp
> and causes any daylight savings rules of the system timezone to be
> ignored. TZInfo will still treat the time value as if it were in local
> time (it ignores the timezone aspect of the Time).

Thanks I suppose I could + "<something-else>".  But I may be getting
confused again, I'd like TZInfo to treat the time as if it were in the
source_tz rather than my local tz.

>
> Passing tz.now as the second argument to Time.parse is required in
> order to make sure you are dealing with the correct date.
>
> > OK this is where I got a little confused - apologies if this is
> > obvious, so it seems to do what I want I can't use 'parse', but
> > instead will have to extract the hrs and minutes, then use:
> >
> > tz = TZInfo::Timezone.get(source_tz)
> > src_time_as_utc = tz.local_to_utc(Time.local(2005,8,29,src_hrs,src_mins,0))
>
> This would work too. TZInfo will just read the year, month, day, hour,
> minute and second of the Time passed to local_to_utc and ignore the
> timezone. It doesn't matter if Time.local returns a different timezone
> to source_tz.

Sorry, I'm confused, I thought that by calling  tz =
TZInfo::Timezone.get(source_tz), it means that in a call to
'tz.local_to_utc' that the 'local in 'local_to_utc' refers to the
source_tz and not the system's tz.  Is this correct?

Regards
Mark

>
> I would use Time.utc instead of Time.local though. If you specified a
> time that fell in a transition between standard and daylight savings
> time of the system timezone, then you might get an unexpected result
> with Time.local.
>
> Regards,
>
> Phil
>
> --
> Phil Ross
> http://tzinfo.rubyforge.org/ -- DST-aware timezone library for Ruby
> _______________________________________________
> TZInfo-users mailing list
> TZInfo-users at rubyforge.org
> http://rubyforge.org/mailman/listinfo/tzinfo-users
>

From phil.ross at gmail.com  Wed Feb  6 15:54:46 2008
From: phil.ross at gmail.com (Philip Ross)
Date: Wed, 6 Feb 2008 20:54:46 +0000
Subject: [TZInfo-users] TzInfo timezone base question
In-Reply-To: <389c43e40802061229n5718a26el5734608b14fa24a9@mail.gmail.com>
References: <389c43e40802060036y2ec676e1g45e6016f962cd0dd@mail.gmail.com>
	<4ac540410802060543w688d5a8cwe5a33e5e23d2cbfb@mail.gmail.com>
	<389c43e40802061146g554f8178oc5ebaada252c307@mail.gmail.com>
	<4ac540410802061211r54600c6fjefaeec756813b511@mail.gmail.com>
	<389c43e40802061229n5718a26el5734608b14fa24a9@mail.gmail.com>
Message-ID: <4ac540410802061254t6cb56049qc65fc0a2d003772d@mail.gmail.com>

On 06/02/2008, Mark Van De Vyver <mvyver at gmail.com> wrote:
> On Feb 7, 2008 7:11 AM, Philip Ross <phil.ross at gmail.com> wrote:
> > There is no equivalent of the parse function in TZInfo. You could use
> > parse and do the following though:
> >
> > tz = TZInfo::Timezone.get(source_tz)
> > src_time_as_utc = tz.local_to_utc(Time.parse("09:30" + " UTC", tz.now))
>
> Sorry I wasn't clearer, but in my case the time string 09:30 refers to
> the source_tz, which is _not_ my local tz nor UTC, and this source tz
> may change in different calls to the method I'm trying to write.  I'd
> like to get a time object that is in the source_tz, but have abandond
> this idea, and will settle for an iso8601 string that contains the
> time in the source tz.

My example does do what you want. "09:30" + " UTC" creates a Time that
is in UTC, but TZInfo treats it as though it were in source_tz.

I'm creating the Time in UTC to avoid any problems that might occur as
a result of daylight savings rules in the system timezone.

> > Adding " UTC" to the time forces it to be parsed as a UTC timestamp
> > and causes any daylight savings rules of the system timezone to be
> > ignored. TZInfo will still treat the time value as if it were in local
> > time (it ignores the timezone aspect of the Time).
>
> Thanks I suppose I could + "<something-else>".  But I may be getting
> confused again, I'd like TZInfo to treat the time as if it were in the
> source_tz rather than my local tz.

When using local_to_utc or any other method that takes a local time as
a parameter, TZInfo will always treat the time as though it were in
source_tz. It ignores any Timezone information in the Time and just
reads the year, month, day, hour, minute and second values.

> > This would work too. TZInfo will just read the year, month, day, hour,
> > minute and second of the Time passed to local_to_utc and ignore the
> > timezone. It doesn't matter if Time.local returns a different timezone
> > to source_tz.
>
> Sorry, I'm confused, I thought that by calling  tz =
> TZInfo::Timezone.get(source_tz), it means that in a call to
> 'tz.local_to_utc' that the 'local in 'local_to_utc' refers to the
> source_tz and not the system's tz.  Is this correct?

Yes, that is correct.

Regards,

Phil

--
Phil Ross
http://tzinfo.rubyforge.org/ -- DST-aware timezone library for Ruby

From mvyver at gmail.com  Wed Feb  6 19:18:16 2008
From: mvyver at gmail.com (Mark Van De Vyver)
Date: Thu, 7 Feb 2008 11:18:16 +1100
Subject: [TZInfo-users] TzInfo timezone base question
In-Reply-To: <4ac540410802061254t6cb56049qc65fc0a2d003772d@mail.gmail.com>
References: <389c43e40802060036y2ec676e1g45e6016f962cd0dd@mail.gmail.com>
	<4ac540410802060543w688d5a8cwe5a33e5e23d2cbfb@mail.gmail.com>
	<389c43e40802061146g554f8178oc5ebaada252c307@mail.gmail.com>
	<4ac540410802061211r54600c6fjefaeec756813b511@mail.gmail.com>
	<389c43e40802061229n5718a26el5734608b14fa24a9@mail.gmail.com>
	<4ac540410802061254t6cb56049qc65fc0a2d003772d@mail.gmail.com>
Message-ID: <389c43e40802061618v3911fa5bqdb29f91fd8c79fda@mail.gmail.com>

Fantastic,  Thanks again fro your patience and efforts.
Regards
Mark
On Feb 7, 2008 7:54 AM, Philip Ross <phil.ross at gmail.com> wrote:
> On 06/02/2008, Mark Van De Vyver <mvyver at gmail.com> wrote:
> > On Feb 7, 2008 7:11 AM, Philip Ross <phil.ross at gmail.com> wrote:
> > > There is no equivalent of the parse function in TZInfo. You could use
> > > parse and do the following though:
> > >
> > > tz = TZInfo::Timezone.get(source_tz)
> > > src_time_as_utc = tz.local_to_utc(Time.parse("09:30" + " UTC", tz.now))
> >
> > Sorry I wasn't clearer, but in my case the time string 09:30 refers to
> > the source_tz, which is _not_ my local tz nor UTC, and this source tz
> > may change in different calls to the method I'm trying to write.  I'd
> > like to get a time object that is in the source_tz, but have abandond
> > this idea, and will settle for an iso8601 string that contains the
> > time in the source tz.
>
> My example does do what you want. "09:30" + " UTC" creates a Time that
> is in UTC, but TZInfo treats it as though it were in source_tz.
>
> I'm creating the Time in UTC to avoid any problems that might occur as
> a result of daylight savings rules in the system timezone.
>
> > > Adding " UTC" to the time forces it to be parsed as a UTC timestamp
> > > and causes any daylight savings rules of the system timezone to be
> > > ignored. TZInfo will still treat the time value as if it were in local
> > > time (it ignores the timezone aspect of the Time).
> >
> > Thanks I suppose I could + "<something-else>".  But I may be getting
> > confused again, I'd like TZInfo to treat the time as if it were in the
> > source_tz rather than my local tz.
>
> When using local_to_utc or any other method that takes a local time as
> a parameter, TZInfo will always treat the time as though it were in
> source_tz. It ignores any Timezone information in the Time and just
> reads the year, month, day, hour, minute and second values.
>
> > > This would work too. TZInfo will just read the year, month, day, hour,
> > > minute and second of the Time passed to local_to_utc and ignore the
> > > timezone. It doesn't matter if Time.local returns a different timezone
> > > to source_tz.
> >
> > Sorry, I'm confused, I thought that by calling  tz =
> > TZInfo::Timezone.get(source_tz), it means that in a call to
> > 'tz.local_to_utc' that the 'local in 'local_to_utc' refers to the
> > source_tz and not the system's tz.  Is this correct?
>
> Yes, that is correct.
>
>
> Regards,
>
> Phil
>
> --
> Phil Ross
> http://tzinfo.rubyforge.org/ -- DST-aware timezone library for Ruby
> _______________________________________________
> TZInfo-users mailing list
> TZInfo-users at rubyforge.org
> http://rubyforge.org/mailman/listinfo/tzinfo-users
>