[Gambas-devel] Gambas 3.10 - gb.web.feed

[Tobias Boege]

On Sat, 22 Jul 2017, Benoît Minisini wrote:
> Le 01/07/2017 à 21:46, Tobias Boege a écrit :
> > On Sat, 01 Jul 2017, Beno�t Minisini via Gambas-devel wrote:
> > > I will have some time next week, and I want to release Gambas 3.10.
> > 
> > Hi Benoit,
> > 
> > Gambas 3.10 would include the new gb.web.feed, right? I have some local
> > changes pending which better be committed before the component is first
> > included in a stable version.
> > 
> > As I mentioned earlier, I want Date values in RSS to be accompanied by
> > an RFC822 timezone string, because I want to give the user a way to
> > specify the timezone string when they create RSS documents (e.g. an RSS
> > feed of a local newspaper in Germany should not have the timezone of
> > the US-located server machine where the feed is put together, but the
> > German timezone relevant to the article).
> > 
> > I need the following:
> > 
> >    1. A way to get the timezone string out of the RFC822 parser in gb.util.
> >    2. Two functions which convert between RFC822 timezone string and
> >       a numeric representation (number of seconds from UTC?) I believe
> >       those functions are already in gb.util, but Private.
> >    3. An RFC822 timezone string for the local system timezone, as a
> >       reasonable default when the user gives no timezone.
> >    4. Functions which convert a (date, timezone) pair, which is to be
> >       understood as "<date> is in/relative to <timezone>" to another
> >       timezone.
> > 
> > I think if 1. and 2. are there, I can implement 3. and 4. by myself.
> > Having 4. would give me a clean conscience, as I intend to store the
> > timezone inside the component just as an RFC822 timezone string and
> > let the user handle calculations with timezones if they need it.
> > Point 4. then gives the user the needed primitives.
> > 
> > Please also look at [1] where I listed some doubts I have about the
> > current RFC822 functions in gb.util.
> > 
> > Regards,
> > Tobi
> > 
> > [1] https://sourceforge.net/p/gambas/mailman/message/35810371/
> > 
> 
> Sorry, I forgot to deal with your requests.
> 

And I came back from vacation just recently. As I see 3.10 wasn't released
yet. I'll try to push the changes today, if we can agree on them.

> You should internally use Gambas date, not strings, as Gambas date are
> internally UTC timestamps.
> 
> The trick is that when you make a date with Date(Year, Month, ...), the
> values you are giving are in the local timezone.
> 
> This is the reason why I'm substracting Frac(Date(Now)): it moves the date
> to the UTC time zone (as Now is in local time, the fractional part of
> Date(Now) converted to float is the timezone).
> 
> Frac(Date(Now)) and -(System.TimeZone / 86400) are the same value (up to the
> 4th decimal digit, because of different precision).
> 
> And isn't the timezone mandatory in a RFC822 date?

Yes, the timezone is mandatory there.

So, how about this: I make a class called RssDate where I store a UTC-based
timestamp (aka Date) and a timezone string. As I mentioned before, I think
the timezone string is necessary to let the user specify what timezone the
date will be printed in.

When an RFC822 date is read, I want to have its timezone string and the
timestamp of that date converted to UTC. When an RFC822 date is written,
I take the UTC timestamp and convert it to the string representation in
the timezone that the user wants to print the date in.

If that sounds reasonable, I can get to work now.

Regards,
Tobi

-- 
"There's an old saying: Don't change anything... ever!" -- Mr. Monk