posical 0.1

A class to assist with doing non-zero math

posical
=======

In 1849 the French philosopher August Comte proposed the *Positivist Calendar*, a new and improved solar calendar with 13 months of 28 days each and 1 epagomenal day outside of the months (2 on leap years). This numbering system had the pleasant effect of maintaining regularity throughout the months and years; every month has the same number of days, and that number is divisible by 7 (the number of days in a week, you might recall), such that any given day of the month (and year) is always the same day of the week.

In addition to this delightfully rational reworking, Msr. Comte saw fit to assign every day to a saint of his own canon—dedicating every day of the year to a great figure in the history of humanity. The months, too, were renamed according to his humanist lights.

Sadly this calendar was not to be used—until now!

`posical.py` is a python 3 library that helps you create datetime-like objects that obey Comte's positivist system, while converting easily from and to our standard Gregorian calendar, and playing nicely with timedelta objects for date math.

But that's not all! The far-sighted creators of `posical` have seen fit to build it in the form of an all-purpose rationalist calendar engine—so now you too can test your mettle when it comes to calendar design. posical calendars can be created according to your whims. And of course dates from competing calendars can get along just fine.

## usage

`posical` requires the `nonzero` package in order to perform sane year-based math. That package is available on PyPi, so you can install it, for instance, with `pip3 install nonzero`.

`posical` can create python calendar objects that contain information about alternate systems to the standard Gregorian calendar.
``` .py
>>> cal = AlternateCal()
>>> print(cal)
The Positivist calendar, consisting of 7-day weeks, 4-week months, and 13-month years, with 1 epagomenal day(s).

```

These calendars can create date objects that are designed to approximate the behavior of standard python `datetime` objects.
``` .py
>>> today = cal.date()
>>> print(today)
Sunday, 21st of Aristotle, 226: SOCRATES
>>> repr(today)
'positivist date(226, 3, 21)'

```

These dates can do date math with each other and with standard `datetime` objects.
``` .py
>>> today - cal.from_date(2014, 3, 30)
datetime.timedelta(-12)
>>> datetime.date(2014,3,25) - today
datetime.timedelta(7)
>>> today + datetime.timedelta(days = 3)
positivist date(226, 3, 24)
>>> today < _
True

```

Comte's Positivist calendar is just the default configuration for a more generalized alternate calendar that can be easily customized. Dates created from one alternate calendar can easily be compared to dates from another.
``` .py
>>> bad_cal = design_calendar()
How many days in a week? 8
How many weeks in a month? 6
When is year 1? 550
>>> print(bad_cal)
The Lycurgian calendar, consisting of 8-day weeks, 6-week months, and 7-month years, with 29 epagomenal day(s).
>>> tomorrow = bad_cal.from_date(2014,3,19)
>>> tomorrow
lycurgian date(1464, 2, 30)
>>> tomorrow - today
datetime.timedelta(1)
```

```
THE POSITIVIST MONTH OF ARISTOTLE, 226
+-------------------------+-------------------------+-------------------------+-------------------------+-------------------------+-------------------------+-------------------------|
|Monday 1|Tuesday 2|Wednesday 3|Thursday 4|Friday 5|Saturday 6|Sunday 7|
| | | | | | | |
| | | | | | | |
| | | | | | | |
| | | | | | | |
| Anaximander| Anaximenes| Heraclitus| Anaxagoras| Democritus| Herodotus| THALES|
+-------------------------+-------------------------+-------------------------+-------------------------+-------------------------+-------------------------+-------------------------|
|Monday 8|Tuesday 9|Wednesday 10|Thursday 11|Friday 12|Saturday 13|Sunday 14|
| | | | | | | |
| | | | | | | |
| | | | | | | |
| | | | | | | |
| Solon| Xenophanes| Empedocles| Thucydides| Archytas| Apollonius of Tyana| PYTHAGORAS|
+-------------------------+-------------------------+-------------------------+-------------------------+-------------------------+-------------------------+-------------------------|
|Monday 15|Tuesday 16|Wednesday 17|Thursday 18|Friday 19|Saturday 20|Sunday 21|
| | | | | | | |
| | | | | | | |
| | | | | | | |
| | | | | | | |
| Aristippus| Antisthenes| Zeno| Cicero| Epictetus| Tacitus| *SOCRATES*|
+-------------------------+-------------------------+-------------------------+-------------------------+-------------------------+-------------------------+-------------------------|
|Monday 22|Tuesday 23|Wednesday 24|Thursday 25|Friday 26|Saturday 27|Sunday 28|
| | | | | | | |
| | | | | | | |
| | | | | | | |
| | | | | | | |
| Xenocrates| Philo of Alexandria| St. John the Evangelist| St. Justin| St.Clement of Alexandria| Origen| PLATO|
```