[Tutor] New keyword ?

[Michele Alzetta]

I'm still fiddling with timespans - only I've just found out that
WxPython has something with the same name but fundamentally different
( WxPythons' is an abstract periods of time, mine is a period with a
precise beginning and end, from which of course the abstract period can
be obtained) .. so I've started calling my class Period.

Besides the _contains_ function, I've added an olaps function which
returns true not only if a period is entirely contained in another, but
also if it overlaps. Here is the code:

-----------------------------------------------------------------
from datetime import datetime, date, timedelta

class Period(object):
    
    def __init__(self, startimetuple, endtimetuple):
        self.starttime = datetime(*startimetuple)
        self.endtime = datetime(*endtimetuple)
	self.isPeriod = True
    
    def __contains__(self, period):
        try:
	    if period.isPeriod:
                return (self.starttime <= period.starttime) and \
                       (self.endtime >= period.endtime)
	except AttributeError:
            moment = datetime(*period)
	    return (self.starttime <= moment <= self.endtime)
    
    def length(self):
        return self.endtime - self.starttime
    
    def olaps(self, period):
        try:
           if period.isPeriod:
                return (( self.starttime < period.starttime \
                < self.endtime) \
                or ( self.starttime < period.endtime < self.endtime ))
        except AttributeError:
                moment = datetime(*period)
                return (self.starttime <= moment \
 		<=    self.endtime)                
    

As I understand it, the 'in' keyword calls my __contains__ function,
e.g.

> week1 in fortnight1
True

Whereas to call my olaps function I have to do this:

> periodinstance.olaps(otherinstance)
True

Is it possible to create a new keyword (say, 'ovlps') to call my
function like this:

> week1 ovlps fortnight
 
If it is possible, would it be desirable ?

-- 
Michele Alzetta <michele.alzetta at aliceposta.it>