Add sign and weekday attributes to vWeekday components

[david-venhoff]

This pr adds the sign and weekday properties to vWeekday components, so that users of this library don't have to manually parse these.

I decided to just make the existing variables available, but I could also combine sign and relative into one variable, if that is wanted.

Fixes: #749

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📚 Documentation preview 📚: https://icalendar--750.org.readthedocs.build/

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Details

• 20 of 20 (100.0%) changed or added relevant lines in 2 files are covered.
• 1 unchanged line in 1 file lost coverage.
• Overall coverage increased (+0.3%) to 96.355%

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Files with Coverage Reduction	New Missed Lines	%
src/icalendar/tests/test_cli_tool.py	1	96.3%

Totals
Change from base Build 11994190464:	0.3%
Covered Lines:	4580
Relevant Lines:	4747

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💛 - Coveralls

[niccokunzmann]

Hi, I like your PR! I left a bot of feedback and I am wondering if the sign should be integrated into the relative variable. What are your thoughts on this?

Also, I am wondering what the sign means and since you care about the sign, I would hope you know and we can document it so others know how to use the fix.

Let me know what you think!
Thanks for the tests!

[niccokunzmann]

I like these examples from the tests.
We also have doctests.
If you add some examples to class definition, this will help people understand your fix and how to use this class.

Like:

>>> su = vWeekday("SU") # Sunday
>>> su
>>> su.weekday
>>> su.relative
>>> su.to_ical()

>>> th = vWeekday("2TH")  # second Thursday of the month?
>>> th
>>> th.weekday
>>> th.relative
>>> th.to_ical()

>>> fr = vWeekday("-1FR")  # last Friday of the month?
>>> fr
>>> fr.weekday
>>> fr.relative

I am writing this here because I would like your input: What does -1 mean in your view? Is it the last weekday of the month?

[david-venhoff]

Yes. For example, this rrule would repeat monthly on every last friday: FREQ=MONTHLY;BYDAY=-1FR. I think using a relative BYDAY value is also allowed with a yearly frequency (rfc, page 42)

[niccokunzmann]

It might be nice to extend the rrule documentation, too. I would say though that I open another issue for that.

[david-venhoff]

I have updated the docstring and added some doctests now :)

[david-venhoff]

I have one more question: According to rfc 5545, the BYDAY attribute for recurrence rules can be followed by a bywdaylist. A bywdaylist can contain weekdaynum, and a weekdaynum is defined like this: weekdaynum = [[plus / minus] ordwk] weekday.
However, some other attributes (e.g. WKST) can only be followed by a simple weekday (without number prefix).

Wouldn't it make sense to have two different classes for weekdays then? One that only stores a weekday and one that stores a weekday and a number. Right now, icalendar always allows the number, I think.

[niccokunzmann]

I think, this is good. One can always create invalid files. this package does not check validity.